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VENTILATION 


AND 

HEATING 


Principles  and  Application 


B.  F.  STURTEVANT  CO. 

BOSTON,  MASS. 

NEW  YORK.  PHILADELPHIA.  CHICAGO. 


Sturtevant  Engineering  Co. 

LONDON.  GLASGOW. 


STOCKHOLM. 


BERLIN. 


MILAN. 


AMSTERDAM. 


CATALOGUE  No.  84. 


COPYRIGHT.  1896,  BY  B.  F.  STURTEVANT  CO. 


SECOND  EDITION. 


PRESS  OF  CARL  H.  HEINTZEMANN.  BOSTON,  MASS. 


INTRODUCTORY 


LTHOUGH  it  is  scarcely  ten  years  since  the  first 
edition  of  this  Treatise  was  issued , this  comparatively 
brief  period  has  witnessed  an  almost  phenomenal 
change  in  public  opinion  regarding  the  absolute  necessity  of 
good  ventilation.  That  the  evil  effects  of  foul  air  are  now 
generally  appreciated  is  best  evidenced  by  the  legal  enactments 
which  control  the  application  of  ventilating  systems  in  many  of 
our  States  and  municipalities.  The  growing  realisation  of  the 
necessity  of  mechanical  means  to  secure  positive  and  reliable 
results  is  likewise  evident  in  the  extensive  and  increasing  in- 
troduction of  the  Sturtevant  System. 

Appreciating  the  value  of  former  editions  of  this  Treatise 
as  a means  of  advancing  the  cause  of  improved  ventilation  and 
of  increasing  the  application  of  the  Sturtevant  System,  it  is  here 
presented  entirely  revised  and  greatly  enlarged,  with  the  sincere 
desire  to  place  before  the  reader,  as  clearly  and  concisely  as 
possible,  the  points  to  be  considered  and  the  steps  to  be  taken  in 
deciding  upon  a system  of  heating  and  ventilation.  The  suc- 
cessful operation  of  the  Sturtevant  System  in  thousands  of 
buildings  in  this  country  and  in  Europe  is  the  best  evidence  we 
have  to  offer  as  to  its  efficiency. 


B.  F.  STURTEVANT  CO. 


' 


ECESSITY  OF  VENTILATION.  Until  quite  recently  ventilation  has  been 


IN  generally  regarded  as  a luxury  rather  than  as  an  absolute  necessity.  The 
discomfort  of  a poorly-ventilated  room  has  been  realized  with  sufficient  vividness, 
but  the  difficulty  of  substituting  for  the  debilitating  atmosphere  one  that  is  pure 
and  invigorating  has  in  many  cases  been  so  far  beyond  the  power  of  ordinary 
methods  to  accomplish  that  a crowded  apartment  and  a vitiated  atmosphere  have 
been  looked  upon  as  inseparable.  But  such  an  atmosphere  is  more  than 
uncomfortable  and  disagreeble ; it  is  positively  and  undeniably  injurious,  and 
continued  exposure  to  it  is  certain  to  lead  to  serious  consequences. 

The  evil  effects  of  lack  of  ventilation  are  made  only  too  evident  by  such 
facts  as  that  “death-rates  have  been  reduced  by  the  introduction  of  efficient 
ventilating  systems,  in  children’s  hospitals,  from  50  to  5 per  cent.;  in  surgical 
wards  of  general  nospitals,  from  44  to  13  per  cent.;  in  army  hospitals,  from  23 
to  6 per  cent.  * * * Prison  records  show  reduced  death-rates,  chiefly 
as  the  result  of  effective  ventilation,  in  one  case  from  the  yearly  average  of 
eighty  deaths  to  one  of  eight,  each  period  covering  the  same  and  a considerable 
number  of  years.  * * * The  annual  death-rate  among  horses  in  army  stables 
in  the  German  service  has  been  reduced  by  more  roomy  quarters  and  free 
ventilation  from  19  to  1.5,  and  in  a time  of  epidemic  in  Boston  the  number  of 
horses  lost  in  badly-ventilated  stables  was  five  to  one  in  those  well  ventilated.”* 

While  such  figures  show  directly  traceable  results  of  breathing  impure  air, 
it  is  not  in  these  most  serious  consequences  alone  that  its  evil  effects  are  revealed. 
A vitiated  atmosphere  lowers  the  vitality,  increases  the  susceptibility  to  and 
severity  of  disease,  and  decreases  the  physical  and  mental  working  power  of  the 

* Notes  on  Ventilation  and  Heating:  Prof.  S.  H.  Woodbridge,  Mass.  Inst.  Tech.,  Boston. 


5 


DEGREES  FAHRENHEIT. 


VENTILATION  and  HEATING 


individual,  and,  while  not  producing  sudden  death,  nevertheless  inevitably 
shortens  life. 

AIR.  Air  being  the  prime  supporter  of  life,  health,  and  even  life  itself,  are 
dependent  upon  the  composition  of  the  atmosphere.  Although  simply  a me- 
chanical mixture,  yet  certain  gases  of  which  it  is  composed  exist  in  almost  un- 
alterable proportions  in  the  normal  atmosphere.  Oxygen  and  nitrogen,  the 
principal  constituents,  are  present  in  very  nearly  the  proportion  of  one  part  of 
oxygen  to  four  parts  of  nitrogen.  Carbonic  acid  gas,  the  result  of  all  combustion, 
either  slow  or  rapid,  exists  in  the  very  small  proportion  of  three  to  four  parts  in 
ten  thousand  of  air,  while  the  aqueous  vapor  varies  greatly  with  the  temperature 
and  exposure  to  water.  In  addition  there  is  generally  present  in  air  in  variable 
but  exceedingly  small  quantities,  ammonia,  sulphureted  hydrogen,  sulphurous  acid 
gas,  floating  organic  and  inorganic  matter  and  local  impurities. 


GRAINS  OF  MOISTURE  PER  CUBIC  FOOT  OF  AIR. 


‘“iSli 

- - 1 / -Jr 

9.  A 

pp 

(ipiii 

Ox  , SO 

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a.  SO  jA  90  / 

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DEGREES  FAHREI 

V r.»  s'  ru  ! 

Sip.;.:  . . . 

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Fig.  i.  Hygrometric  Chart. 


HUMIDITY.  The  condition  of  the  atmosphere  with  relation  to  the  amount 
of  vapor  or  water  which  it  holds  in  suspension  is  expressed  by  the  term  humidity. 
Actual  Humidity  relates  to  the  actual  weight  of  water  vapor  present  in  a given 
unit  volume  of  air,  while  the  term  Relative  Humidity  expresses  the  relation  be- 
tween the  vapor  actually  present  in  the  air  and  that  which  it  would  contain  if 
saturated.  Obviously  the  air  is  saturated  with  moisture  when  it  will  hold  no 
more.  The  actual  humidity  varies  excessively  with  the  temperature;  it  is,  there- 
fore, evident  that  a statement  of  the  relative  humidity  gives  no  indication  of  the 


6 


TABLE  No.  1. 

Of  the  Weights  of  Air,  Vapor  of  Water,  and  Saturated 
Mixtures  of  Air  and  Vapor  at  Different  Tempera- 
tures, UNDER  THE  ORDINARY  ATMOSPHERIC  PRES- 
SURE of  29.921  Inches  of  Mercury. 


b u ° 

<J  a|  8' 

2 W > b£ 

MIXTURES  OF  AIR  SATURATED  WITH  VAPOR. 

0 t 2 

<V  m 

‘tu 

-*= 

3.S  fe-O 

« >>5  2 

s s! 

g-g 

C > 

0 c ^ r 3 

WEIGHT  OF  CUBIC  FOOT  OF  THE 

MIXTURE  OF  AIK  AND  VAPOR. 

*>*5  * 

t-5  5 

O'g 

9-' « 3 . 

CC  8 5 

<D  CD 

cl  t: 
E 

1=“- 

Volume  of 
at  different 
atures,  tlie 
at  ^2°  bein 

Weight  of 
Foot  of  Dr 
different  t 
tures,  in  j 

Elastic  F 
Vapor  in  ii 
Mercury,  II 

Elastic  F 
of  the  Air  i 
Mixture  of 
and  Vapo 
ins.  of  Mer 

Weight  of 
the  Air  in 
pounds. 

Weight  of 
the  Vapor 
in  pounds 

Total 
Weight  of 
Mixture  l 
in  pounds 

U-t  O 

0 c 
<U  3 

c c, 

« - 
> c 

Weight  of 
Air  mixed 

1 lb.  of  V 
in  pounc 

Cubic  Ft.  c 
from  1 lb.  0 
at  its  own  \ 
in  colur 

i 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

0° 

•935 

.0S64 

•°44 

29.S77 

.0S63 

.000079 

•0S6379 

.00092 

1092.4 

12 

.960 

.0S42 

•°74 

29.S49 

.0840 

.000130 

.0S4130 

■00155 

646.1 

22 

.9S0 

.0S24 

. I l8 

29.S03 

.0821 

.000202 

.082302 

.00245 

406.4 

32 

I .OOO 

.0S07 

. 1S1 

29.740 

.0S02 

.OOO304 

.0S0504 

.00379 

263. Si 

3289 

42 

1 .020 

.0791 

.267 

29.654 

-°7S4 

. ooo-}  40 

.07SS40 

.00561 

178.  iS 

2252 

52 

1 .041 

.0776 

•3SS 

29  533 

.0766 

.000627 

.077227 

.00S19 

122.17 

1595 

62 

1. 061 

.0761 

•556 

29-365 

•°747 

.000SS1 

•o755Si 

.01179 

S4.79 

ii35 

72 

1.0S2 

•°747 

•7S5 

29.136 

.0727 

.00122 I 

.073921 

.016S0 

59-54 

S19 

82 

1 .102 

■°733 

1 .092 

28.829 

.0706 

.001667 

.072267 

.02361 

42*35 

600 

92 

1.122 

.0720 

1 -501 

2S.420 

.06S4 

.002250 

.070717 

.032S9 

30.40 

444 

102 

i-i43 

.0707 

2.036 

27-885 

.0659 

.002997 

.06SS97 

•04547 

2 1. 98 

334 

112 

1.163 

.0694 

-■731 

27.190 

.0631 

.003946 

.067046 

.06253 

J5-99 

253 

122 

1.1S4 

.06S2 

3.621 

26.300 

■0.599 

.005142 

.065042 

.0S5S4 

11.65 

194 

132 

1.204 

.0671 

4*752 

25.169 

.0564 

.006639 

.063039 

.11771 

S-49 

151 

142 

1.224 

.0660 

6.165 

23-756 

•0524 

•00S473 

.060873 

.16170 

6.1S 

118 

152 

J--45 

.0649 

7-930 

2I.99I 

•°477 

.010716 

.05S416 

.22465 

4-45 

93-3 

162 

1.265 

•063S 

IO.O99 

19.822 

■0423 

•OI34I5 

°557‘5 

■31713 

3-iS 

74-5 

172 

i--S5 

.062S 

12.75S 

17.163 

.0360 

.016682 

.0526S2 

•46338 

2.l6 

59-2 

182 

1.306 

.o6iS 

15.960 

13.961 

.02SS 

.020536 

•049336 

•7I3°0 

1.402 

4S.6 

192 

1.326 

.0609 

19.S2S 

10.093 

0205 

.025142 

.045642 

1.22643 

•S15 

39-8 

202 

i-347 

.0600 

24.450 

5-471 

.OIO9 

•030545 

.041445 

2.S023P 

•357 

32.7 

212 

1-367 

.0591 

29.921 

0.000 

.OOOO 

.036820 

.036820 

Infinite. 

.OOO 

27.1 

/ 


VENTILATION  and  HEATING 


exact  amount  of  vapor  present  unless  the  moisture  carrying  capacity  of  the  air  at 
the  given  temperature  be  known. 

The  accompanying  Table  No.  1 gives  a clear  idea  of  the  relations  existing 
between  the  weights  of  air  and  vapor,  in  saturated  mixtures  at  different  tem- 
peratures, and  will  be  found  exceedingly  useful  in  all  calculations  relating  to 
heating  and  drying. 

A portion  of  this  table  is  more  clearly  represented  graphically  by  the  hygro- 
metric  chart,  Fig.  1,  the  rapid  increase  in  the  capacity  of  the  air  for  carrying  off 
moisture,  as  the  temperature  of  the  air  rises,  being  indicated  by  the  curved  lines, 
which  represent  10,  20,  etc.,  to  100  per  cent,  humidity:  100  per  cent,  being  the 
dew  point.  The  horizontal  line  of  figures,  from  10  to  200,  at  the  top  of  the 
chart,  indicates  the  grains  of  moisture  per  cubic  foot  of  air,  while  the  temperature 
of  the  air  is  given  in  degrees  Fahrenheit  at  the  left  of  the  chart. 

CARBONIC  ACID  GAS.  This  gas  is  of  itself  only  a neutral  constituent 
of  the  atmosphere,  like  nitrogen,  and,  contrary  to  general  impressions,  its  un- 
associated presence  in  moderately  large  quantities  — as  in  soda-water  manufacto- 
ries— is  neither  disagreeable  nor  particularly  harmful.  But  its  presence  in  the 
air  provided  for  respiration  decreases  the  readiness  with  which  the  carbon  of  the 
blood  unites  with  the  oxygen  of  the  air  to  form,  in  the  lungs,  further  amounts 
of  carbonic  acid.  It  is  evident,  therefore,  that  when  present  in  sufficient  quantity, 
it  may  indirectly  bring  about  not  only  serious  but  fatal  results.  The  true  evil  of 
a vitiated  atmosphere  lies  in  its  other  constituent  gases  and  in  the  micro-organisms 
which  are  produced  in  the  process  of  respiration.  It  is  known,  however,  that 
these  other  impurities  exist  in  fixed  proportion  to  the  amount  of  carbonic  acid 
present  in  an  atmosphere  vitiated  by  respiration. 

Therefore,  as  the  relative  proportion  of  carbonic  acid  may  be  easily  deter- 
mined by  experiment,  the  fixing  of  a standard  limit  of  the  amount  in  which  it 
may  be  allowed  in  ventilated  rooms  also  limits  the  permissible  vitiation  of  the 
atmosphere  by  other  impurities. 

When  carbonic  acid  is  present  in  excess  of  10  parts  to  10,000  parts  of  air, 
a feeling  of  weariness  and  stuffiness,  generally  accompanied  by  a headache,  will 
be  experienced,  while  even  with  8 parts  in  10,000  parts  a room  would  be  con- 
sidered close.  For  general  considerations  of  ventilation  the  limit  should  be 
placed  at  6 to  7 parts  in  10,000,  thus  allowing  an  increase  of  2 to  3 parts  per 
10,000  over  that  present  in  outdoor  air,  which  may  be  considered  to  contain 
4 parts  in  10,000  under  the  ordinary  conditions  of  a populous  district. 

The  exceedingly  bad  condition  of  the  air  in  many  halls  and  theatres  is 


8 


VENTILATION  and  HEATING 


demonstrated  by  the  following  results  of  experiments  by  Professor  Woodbridge 
in  various  buildings  in  Boston.* 

Place  and  Time.  Parts  of  Carbonic  Acid  Gas  in  10,000  Parts  of  Air. 


/ 1st  Test, 

Floor. 

First  Balcony. 

Second  Balcony. 

Gallery. 

4S.7 

Boston  Theatre,  j 2d  Test 

39.13 

42.86 

44.72 

48.14 

t 3d  Test, 

— 

3548 

— 

45.12 

Globe  Theatre.  / Three-fourths  full, 

23.38 

35.88 

34.59 

— 

l One-half  full 

19. 

24.16 

24.72 

— 

Huntington  Hall. — Ventilating  apparatus  unused 18.48  to  17.24 

Young  Men’s  Christian  Association 36.43  to  32.59 

Trinity  Church. — Gallery 20.52  to  19.12 


In  these  cases  injurious  effects  could  not  fail  to  ensue  from  a continued 
exposure  to  such  seriously  contaminated  air. 


AMOUNT  OF  AIR  REQUIRED  FOR  VENTILATION.  Under  the 
general  conditions  of  outdoor  air,  namely  70°  temperature  and  70  per  cent,  of 
complete  saturation,  an  average  adult  man,  when  sitting  at  rest  as  in  an  audience, 
makes  16  respirations  per  minute  of  30  cubic  inches  each,  or  480  cubic  inches 
per  minute.  Under  the  previously  assumed  conditions  of  70°  temperature  and 
70  per  cent,  humidity,  the  air  thus  inhaled  will  consist  of  about  i oxygen  and 
i nitrogen,  together  with  about  liV  per  cent,  aqueous  vapor  and  riU  of  a 
per  cent,  carbonic  acid.  By  the  process  of  respiration  the  air  will,  when  exhaled, 
be  found  to  have  lost  about  i of  its  oxygen  by  the  formation  of  carbonic  acid, 
which  will  have  increased  about  one  hundred-fold,  thus  forming  about  4 per 
cent.,  while  the  water  vapor  will  form  about  5 per  cent,  of  the  volume,  in  ad- 
dition, the  inhaled  air  will  have  been  warmed  from  70°  to  90°,  and,  notwith- 
standing the  increased  proportion  of  carbonic  acid, — which  is  about  one  and 
one-half  times  heavier  than  air, — will,  owing  to  the  increase  of  temperature  and 
the  levity  of  the  water  vapor,  be  about  3 per  cent,  lighter  than  when  inhaled. 
Thus  it  will  be  seen  that  this  vitiated  air  will  not  fall  to  the  ground,  as  has  often 
been  presumed,  but  will  naturally  rise  above  the  level  of  the  breathing  line,  and 
the  carbonic  acid  will  immediately  diffuse  itself  into  the  surrounding  air.  In  ad- 
dition to  the  carbonic  acid  exhaled  in  the  process  of  respiration,  a small  amount 
is  given  off  by  the  skin.  Furthermore,  G to  2\  lbs.  of  water  are  evaporated 
daily  from  the  surface  of  the  skin  of  a person  in  still  life.  If  the  air  supply  at 
70°  is  assumed  to  have  a humidity  of  70  per  cent,  and  to  be  saturated  when  it 
leaves  the  body  at  a higher  temperature,  then  at  least  4 cubic  feet  of  air  per 
minute  will  be  required  to  carry  away  this  vapor. 

* Technology  Quarterly,  Vol.  II.  No.  2. 


9 


VENTILATION  and  HEATING 


Taking  into  consideration  these  various  factors,  it  becomes  evident  that  at 
least  4i  cubic  feet  of  fresh  air  will  be  required  per  minute  for  respiration  and 
for  the  absorption  of  moisture  and  dilution  of  carbonic  acid  gas  from  the 
skin.  This,  however,  is  only  on  the  assumption  that  any  given  quantity  of  air 
having  fulfilled  its  office,  is  immediately  removed  without  contamination  of  the 
surrounding  atmosphere;  but  this  condition  is  impossible,  for  the  spent  air  from 
the  lungs,  containing  about  400  parts  of  carbonic  acid  gas  in  10,000,  is  immedi- 
ately diffused  in  the  atmosphere.  The  carbonic  acid  does  not  fall  to  the  floor  as 
a separate  gas,  but  is  intimately  mixed  with  the  air  and  equally  distributed 
throughout  the  apartment. 

It  must  then  be  evident  that  ventilation  is  in  effect  but  a process  of  dilution 
and  that  when  the  vitiation  of  the  air  discharged  from  the  lungs  is  known  and  the 
degree  of  vitiation  to  be  maintained  in  the  apartments  is  decided,  the  necessary  con- 
stant supply  of  fresh  air  to  maintain  this  standard  may  be  very  easily  determined. 
For  the  purpose  of  calculation,  0.6  cubic  feet  per  hour  is  accepted  as  the 
average  production  of  carbonic  acid  by  an  adult  at  rest  and  the  proportion  of  this 
gas  in  the  external  air  as  4 parts  in  10,000.  If,  therefore,  the  degree  of  vitiation 
of  the  occupied  room  be  maintained  at,  say,  6 parts  in  10,000,  there  will  be  per- 
missible an  increment  of  only  2 parts  in  10,000  above  that  of  the  normal 
atmosphere,  or  2- 10, 000=. 0002  of  a cubic  foot  of  carbonic  acid  in  each  cubic 
foot  of  air.  The  0.6  cubic  foot  of  carbonic  acid  produced  per  hour  by  a single 
individual  will,  therefore,  require  for  its  dilution  to  this  degree  0.6-F.0002=3,000 
cubic  feet  of  air  per  hour.  Upon  this  basis  the  following  Table  has  been  calculated : 


Cubic  Feet  of  Air  Con- 
taining 4 Parts  of 
Carbonic  Acid  in  to,- 

Per 

Hour. 

o 

VO 

8 

■*r 

3000 

2400 

3 

Q 

Cl 

8 

C/D 

’rt 

u 

o 

© 

12C0 

Q 

d 

l/“; 

Cl 

ro 

ro 

Cl 

000  Supplied  per  Per 
son 

a-S 

too 

66.6 

50 

40 

33.3 

30 

2S.6 

25 

20 

16.6 

9.1 

6.2 

3.8 

Degree  of  Vitiation  of 
the  Air  in  the  Room. 

- o C 

S J.~ 

5 

5-5 

6 

6.5 

7 

7.33 

7-5 

8 

9 

10 

15 

20 

30 

The  figures  indicate  absolute  relations  under  the  stated  conditions,  and  are 
generally  applicable  to  the  ventilation  of  schools,  churches,  halls  of  audience  and 
the  like,  where  the  occupants  are  reasonably  healthy  and  remain  at  rest.  But 
the  absolute  air  volume  to  be  supplied  cannot  be  specified  with  certainty  in  ad- 
vance, without  a thorough  knowledge  of  all  the  conditions  and  modifying  circum- 


10 


stances, — in  fact,  the  climate,  the  construction  of  the  building,  the  size  of  the 
rooms,  the  number  of  occupants,  their  healthfulness  and  their  activity,  together 
with  the  time  during  which  the  rooms  are  occupied,  all  have  their  direct  influences. 
Under  all  these  considerations,  it  is  readily  seen  that  no  standard  allowance  can 
be  made  to  suit  all  circumstances,  and  results  will  be  satisfactory  only  in  so  far  as 
the  designer  understandingly,  with  the  knowledge  of  the  various  requirements  as 
they  have  here  been  given,  makes  such  allowance.  The  following  schedule  of 
air  supply,  in  cubic  feet  per  hour,  as  proposed  by  Dr.  Billings*  is  here  presented 
as  showing  relatively  the  volumes  recommended  by  him  in  different  classes  of 
buildings : 


Cubic  Feet  per  Hour. 


3,600  per  Bed 
3,600  per  Seat 


Hospitals, 

Legislative  Assembly  Halls, 

Barracks,  Bedrooms  and  Workshops, 
Schools  and  Churches, 

Theatres  and  Ordinary  Halls  of  Audience 

Office  Rooms 

Dining  Rooms,  . . . . . 


3.000  per  Person 
2,400  per  Person 

2.000  per  Seat 


1,800  per  Person 
1,800  per  Person 


These  figures  are  for  buildings  in  which  there  is  no  special  contamination  of 
the  atmosphere  beyond  that  which  their  use  would  indicate.  Where  smoke, 
dust,  noxious  gases  or  infectious  germs  are  produced,  and  above  all  where  the 
illumination  is  furnished  by  candles,  lamps  or  gas,  additional  provision  of  air 
supply  must  be  made.  Thus  a single  4 1-2  gas  burner  demands  45  cubic  feet  of 
air  per  minute  and  the  resulting  carbonic  acid  gas,  unless  sufficiently  diluted,  or 
immediately  removed,  will  seriously  vitiate  the  air.  The  introduction  of  modern 
methods  of  incandescent  electric  lighting  has  done  much  to  simplify  and  facilitate 
the  solution  of  problems  in  heating  and  ventilation. 

The  air  volumes  recommended  for  ventilation  by  various  investigators  of  the 
past  century  show  a constant  increase  in  their  quantity  as  the  years  progress.  As 
good  ventilation  is  only  a relative  term,  depending  largely  on  one’s  experience 
and  the  possibility  of  improvement,  it  must  be  evident  that  perfect  ventilation  in 
the  broadest  sense  can  only  be  secured  in  the  open  air.  It  is,  therefore,  the 
province  of  ventilation  to  approach  as  near  this  perfection  as  means  and 
expediency  will  permit. 

The  crystallization  of  public  opinion  into  statute  laws,  looking  to  adequate 
methods  of  ventilation  for  school,  theatre,  church  and  factory,  has  resulted  in 
the  establishment  of  a basis  or  limit  which  will  meet  the  approval  of  those  upon 
whom  is  placed  the  responsibility  of  enforcing  these  laws.  Under  the  law  as  first 


Ventilation  and  Heating:  JohnS.  Billings,  New  York,  1SQ3. 

it 


VENTILATION  and  HEATING 


passed  in  Massachusetts,  the  attempt  was  made  to  secure  50  cubic  feet  per  head 
per  minute,  but  it  was  soon  discovered  that  such  provision  would  necessitate  the 
remodelling  of  practically  every  building  in  the  State.  Therefore,  financial  out- 
weighed all  other  influences,  and  the  limit  was  dropped  to  30  cubic  feet,  a figure 
adopted  not  because  of  hygienic  deductions  but  because  it  appeared  upon  investi- 
gation to  be  the  practical  limit  attained  by  existing  methods  in  the  common- 
wealth. 

This  basis  of  30  cubic  feet  has  been  very  generally  adopted  throughout  the 
country,  and  is  to-day  recognized  as  the  minimum  volume  to  be  provided  in  any 
system  of  ventilation  worthy  of  the  name.  As  the  benefits  of  good  ventilation 
are  still  further  recognized,  and  the  ability  of  the  fan  to  provide  practically 
unlimited  volumes  of  air  is  better  appreciated,  this  limit  will  gradually  rise  until 
we  may  one  day  witness  the  compulsory  provision  of  air  for  the  purpose  of 
ventilation  in  such  volumes  as  to  render  further  improvement  of  no  practical 
benefit. 


12 


VENTILATION  and  HEATING 

153CS5 


HEATING. 

HEAT  OF  HUMAN  BODY.  The  normal  internal  temperature  of  the 
human  body  is  very  near  100°,  independent  of  the  temperature  of  the 
surrounding'  air.  By  respiration  the  continuous  process  of  slow  combustion  is 
kept  up, — the  oxygen  of  the  air,  uniting  with  the  carbon  of  the  blood  passing 
through  the  lungs,  to  form  carbonic  acid.  As  in  any  case  of  combustion,  over- 
heating takes  place  unless  provision  is  made  for  the  distribution  of  the  heat 
generated,  so  the  body  is  kept  at  its  normal  temperature  only  by  the  abstraction 
of  heat  from  it.  The  actual  heating  of  the  body  is  not  the  ultimate  object  of 
heating;  but,  in  reality,  provision  is  made  for  the  abstraction  of  heat  generated 
by  the  vital  functions  without  making  too  great  a demand  upon  the  physical 
endurance  ot  the  individual. 

MEANS  OF  DISPERSION  OF  HEAT.  Three  means  are  provided  for 
the  healthful  dispersion  of  heat  from  the  human  body.  First.  By  radiation  to 
the  air  and  surrounding  objects.  Second.  By  conduction,  principally  to  the  air 
immediately  in  contact  with  the  body.  Third.  By  evaporation  of  moisture 
from  the  lungs,  throat  and  skin.  Under  the  conditions  of  summer  air,  the  last 
two  are  generally  about  equal,  but  the  greater  part  of  the  heat  is  dissipated  by 
the  first  means.  Air  is  a nearly  perfect  non-conductor  of  heat,  but  radiation 
takes  place  through  it  readily.  We  may  enter  a room  having  a temperature  of 
75°,  with  walls  at  50°,  and  feel  chilled,  simply  because  heat  is  rapidly  radiated 
from  the  body  through  the  air  to  the  colder  walls.  In  comparatively  dry  air 
equality  of  temperature  is  kept  up  by  a steady  but  imperceptible  evaporation 
from  the  skin.  In  moist  air  this  rapid  evaporation  is  prevented  and  the  water 
is  deposited  as  perspiration,  the  air  being  too  heavily  laden  to  take  it  up.  On 
the  other  hand,  when  the  air  is  in  motion  it  increases  both  evaporation  and 
conduction  by  the  constant  bringing  of  fresh  air  to  take  the  place  of  that  already 
moistened  or  heated.  If,  under  any  circumstances,  one  of  these  three  means 
fails  to  abstract  heat  rapidly  enough,  the  removal  by  the  other  means  is  increased, 
and  equilibrium  of  temperature  kept  up. 


VENTILATION  and  HEATING 


High  humidity  has  the  effect  of  modifying  very  materially  the  temperature 
at  which  comfort  may  be  secured.  The  excessive  humidity  of  the  atmosphere 
of  the  west  and  south  of  England  has,  owing  to  the  reduced  evaporation  from 
the  body,  the  effect  of  making  a temperature  of  56°  in  that  country  equally  as 
comfortable  as  80°  in  the  dryer  climate  of  Canada  or  Minnesota. 

In  this  country,  where  some  means  of  heating  is  usually  required  during 
about  seven  months  of  the  year,  the  amount  of  heat  necessary  and  the  economy 
exercised  in  supplying  it  are  vital  questions.  As  will  appear  in  what  follows, 
convenience  and  economy  can  best  be  secured  by  an  intelligent  union  of  the 
heating  and  ventilating  systems. 


l i 


SYSTEMS  OF 


VENTILATION  AND  HEATING. 


ATURAL  METHODS.  The  requirements  of  good  ventilation  and  heating 


IN  being  understood,  the  choice  of  the  best  method  for  carrying  out  such 
requirements  presents  itself.  While  the  principles  have  been  generally  under- 
stood, their  application  has  proved  to  be  the  stumbling-block  over  which  many 
an  architect  and  engineer  has  tripped.  Natural  agencies,  as  apparently  the  least 
expensive,  have  usually  been  first  called  upon  to  produce  such  currents  and  move 
such  volumes  of  air  as  might  be  required.  But  it  will  be  universally  admitted 
that  all  systems  of  so-called  “ natural  ventilation  ” have  proved  themselves 
inadequate  to  fulfill  all  requirements.  A dependence  upon  windows  and  doors 
for  ventilation  cannot,  with  propriety,  be  called  a system  of  ventilation,  for  the 
supply  is  ordinarily  spasmodic,  and,  without  question,  disagreeable,  except  in  so 
far  as  a cold  draught  of  fresh  air  from  an  open  window  may  be  preferable  to  the 
vitiated  and  odorous  air  of  a confined  apartment.  Excellent  results  may  con- 
tinue for  a number  of  days  during  the  employment  of  a method  of  ventilation 
dependent  upon  natural  agencies,  but  a change  in  the  temperature  or  humidity, 
or  in  the  direction  and  force  of  the  wind,  may  exactly  reverse  the  action  of  the 
system.  Flues  which  were  designed  to  furnish  fresh  air  will  be  found  to  be 
actionless,  while  foul-air  ducts  may  be  bringing  the  foul  air  from  other  rooms. 
For  a crowded  or  continuously-occupied  apartment,  such  arrangements  are  utterly 
inadequate  and  are  certain  to  prove  entirely  unequal  to  the  task  of  supplying  air  in 
such  quantity  as  has  been  shown  to  be  required, — above  all,  they  are  not  positive. 

VENTILATION  BY  ASPIRATION.  Somewhat  more  positive  results  may 
be  obtained  by  warming  the  air  within  the  vent  flues.  Gas-jets,  steam-heated 
surfaces  and  the  smoke  flues  from  steam  or  hot-air  furnaces,  are  employed  for 
this  purpose.  But  as  the  results  attained  are  due  to  a lessened  density  of  the  air 
within  the  flue,  and  as  the  heat  applied  for  thus  warming  and  rarifying  this  air 
serves  no  other  useful  purpose  but  is  dissipated  in  the  atmosphere,  the  method 
proves  to  be  excessively  expensive  when  the  power,  as  measured  in  heat  units, 
required  to  develop  this  movement  is  taken  into  account. 


15 


VENTILATION  and  HEATING 


FORCED  CIRCULATION.  In  the  system  of  forced  circulation  by  means 
of  that  universally-adopted  machine, — a fan  or  blower, — the  action  is  absolute 
and  positive.  The  whole  matter  cannot  be  better  expressed  than  in  the  words 
of  the  late  Robert  Briggs,*  a man  of  large  experience  in  practical  ventilation 
and  heating:  “ It  will  not  be  attempted  at  this  time  to  argue  fully  the  advantages 
of  the  method  of  supplying  air  for  ventilation  by  impulse  through  mechanical 
means, — the  superiority  of  forced  ventilation,  as  it  is  called.  This  mooted 
question  will  be  found  to  have  been  discussed,  argued  and  combated  on  all  sides, 
in  numerous  publications,  but  the  conclusion  of  all  is,  that  if  air  is  wanted  in 
any  particular  place,  at  any  particular  time,  it  must  be  put  there,  not  allowed 
to  go.  Other  methods  will  give  results  at  certain  times  or  seasons,  or  under 
certain  conditions.  One  method  will  work  perfectly  with  certain  differences 
of  internal  and  external  temperatures,  while  another  method  succeeds  only  when 
other  differences  exist.  One  method  reaches  to  relative  success  whenever  a wind 
can  render  a cowl  efficient.  Another  method  remains  perfect  as  a system  if  no 
malicious  person  opens  a door  or  window.  No  other  method  than  that  of 
impelling  air  by  direct  means,  with  a fan,  is  equally  independent  of  accidental 
natural  conditions,  equally  efficient  for  a desired  result,  or  equally  controllable  to 
suit  the  demands  of  those  who  are  ventilated.” 


EFFICIENCY  OF  THE  FAN.  Further  on  in  the  same  paper,  Mr.  Briggs 
states  that : — “ In  all  mechanical  appliances,  that  is  simplest  which  most  positively 
and  directly  effects  the  purpose  in  view ; and  in  this  matter  of  supplying  air,  it 
may  be  claimed  that  the  process  of  impelling  it,  when  and  where  wanted,  is  at 
once  the  most  certain  and  efficient,  and  that  the  fan  (in  its  form  of  a rotating 
wheel  with  vanes  for  large  uses),  is  the  simplest  and  readiest  machine  for 
impelling  air.  It  will  not  be  attempted  at  this  time  to  discuss  the  theory  of 
Rotary  Fans.  The  fan  itself  will  simply  be  accepted  as  one  of  the  recognized 
appliances  in  the  construction  of  ventilating  apparatuses,  available  with  other 
mechanisms  in  established  forms  and  defined  types  for  American  practice.” 

After  showing  the  enormous  expense  of  moving  air  by  allowing  it  to  pass 
over  steam-heated  surfaces  (thus  creating  a difference  in  pressure  due  to  a differ- 
ence in  temperature)  compared  with  the  expense  of  moving  equal  quantities  of 
air  by  means  of  a fan,  Prof.  S.  H.  Woodbridge,t  of  the  Massachusetts  Institute 
of  Technology,  states  that  “ among  the  many  mechanical  devices  for  the  move- 
ment of  air  through  channels,  none  are  so  economical  of  power  and  convenient 
in  use  as  the  fan.” 

*Oti  the  Ventilation  of  Halls  of  Audience  : Robert  Briggs;  Proc.  Am.  Soc.  Civil  Engineers,  May,  1SS1. 
t Notes  on  Ventilation  and  Heating:  Prof.  S.  H.  Woodbridge,  Mass.  Inst.  Tech.,  Boston. 

16 


VENTILATION  and  HEAT1NG« 

A practical  illustration  will  best  serve  to  prove  the  force  of  this  statement. 
A vent  flue,  one  square  foot  in  cross  sectional  area  and  40  feet  high,  is  arranged 
to  withdraw  air  from  a room  having  a temperature  of  70°  while  the  outdoor  air 
is  at  20°  ; the  flue  being  provided  with  an  accelerating  coil,  which  heats  the  air 
within  to  90°.  By  the  ordinary  methods  of  calculation,  it  may  be  shown  that 
the  theoretical  velocity  of  the  air  thus  produced  in  the  tine  will  be  1,149-4  feet 
per  minute,  and  that  there  will  be  expended  for  its  movement  394.6  heat  units. 
A fan,  on  the  other  hand,  would  theoretically  require,  to  produce  the  same  air 
movement,  only  .703  units  of  heat.  But  these  figures  are  purely  theoretical,  and 
the  efficiency  of  the  two  methods  must  enter  to  give  the  true  relation. 

Assuming  for  the  flue  an  average  efficiency  of  60  per  cent.,  there  will 
actually  be  required  for  this  method  657.7  units  of  heat.  On  the  other  hand, 
making  the  fair  assumptions  that  of  the  heat  units  in  the  fuel  70  per  cent,  is 
delivered  in  the  form  of  steam,  that  this  steam  is  utilized  in  an  engine  having  an 
efficiency  of  only  10  per  cent.,  while  the  fan  driven  thereby  turns  into  useful 
work  only  2 5 per  cent,  of  the  power  delivered  to  it  by  the  engine,  the  combined 
efficiency  of  the  system  will  be  reduced  to  1.75  per  cent.,  calling  for  a heat 
expenditure  of  40.17  units.  Even  under  this  practical  condition,  it  appears  that 
the  movement  of  air  by  aspiration  still  requires  1 6.3 7 times  as  much  heat  (which 
is  simply  a measure  of  the  coal  bill),  as  a fan  producing  the  same  results.  Of 
course,  a change  in  the  conditions  will  affect  this  relation  to  a reasonable  extent, 
but  it  is  certainly  evident  that  the  thermal  or  aspiration  system  requires  more 
fuel  than  the  fan  under  all  practical  conditions  as  they  exist  in  any  system  of 
heating  and  ventilation. 

METHODS  OF  HEATING.  In  the  progress  of  civilization  more  efficient 
arrangements  for  heating  have  gradually  been  adopted.  Fireplaces,  stoves  and 
furnaces  have,  in  the  order  named,  been  introduced  as  means  of  warming.  For 
small  rooms,  as  in  dwellings,  they  answer  very  well ; but  the  effect  of  opening 
or  closing  windows  and  doors  and  of  changes  in  the  atmospheric  conditions  is 
too  well  appreciated  to  need  recital  here.  It  will  certainly  be  admitted  that  a 
building  can  seldom  be  found  where  the  heated  air  is  properly  and  satisfactorily 
furnished  and  distributed  by  a furnace  ; some  of  these  influences  are  sure  to  act, 
and  at  times  it  will  be  impossible  to  heat  certain  rooms  without  the  closing  of 
doors  or  shutting  of  registers  in  other  rooms. 

More  refined  are  the  methods  of  heating  which  are  dependent  upon  the  use 
of  steam  or  hot  water,  confined  in  radiators  or  coils.  Under  systems  of  direct 
radiation,  these  are  placed  in  the  rooms  to  be  heated,  but  seldom  with  any 


17 


VENTILATION  and  HEATING 


provision  for  the  introduction  of  fresh  air.  By  the  indirect  method  of  placing 
the  heating  surface  in  ducts  connecting  with  the  rooms  and  permitting  outdoor 
air  to  pass  across  such  surfaces,  a much  nearer  approach  is  made  to  good 
ventilation.  But  still  it  is  practically  impossible  by  such  means  alone  to  produce 
the  air-tlow  and  maintain  the  temperature  necessary  for  a large  and  crowded 
apartment.  It  is  evident  that  some  positive  means,  like  the  fan,  must  be  applied 
to  render  such  systems  reliable  at  all  times. 


VENTILATION  AND  HEATING  COMBINED.  Experience  has  clearly 
demonstrated  that  in  this  climate  no  system  of  ventilation  can  be  successfully 
operated  by  itself  and  independently  of  the  method  of  heating  that  may  be 
adopted.  It  is,  in  fact,  a vital  element  of  success  that  the  two  systems  be  most 
intimately  combined,  for  they  are  clearly  interdependent,  and  when  properly 
applied  are  so  interwoven  in  their  operation  and  results  that  disunion  is  certain 
to  bring  about  failure.  For  the  purpose  of  ventilation,  the  fan  was  first  applied 
upon  a practical  scale  about  the  middle  of  this  century,  but  only  to  a limited 
extent,  and  it  was  not  until  the  fan  and  the  steam  heater  in  marketable  form 
were  introduced  by  B.  F.  Sturtevant  that  the  so-called  “ Blower  System  ” became 
a reality.  The  System,  of  which  these  two  elements  are  the  most  important 
factors,  as  originally  installed  by  this  house,  has  naturally  been  known  as 
“The  Sturtevant  System.”  This  System  is  at  once  practical,  successful  and 
economical ; for,  air  being  the  natural  conveyor  of  heat,  it  may,  when  properly 
warmed  and  supplied,  perform  the  double  office  of  heating  and  ventilating.  As 
applied,  the  Sturtevant  System  forces  the  air  into  the  apartment  by  the  pres- 
sure or  plenum  method.  When  a fan  is  arranged  to  exhaust  or  withdraw  the 
air  from  an  enclosed  space,  the  term  vacuum,  or  exhaust  method , is  almost 
universally  applied. 

THE  EXHAUST  METHOD.  There  are  many  objections  to  the  adoption 
of  the  exhaust  method  in  this  country,  and,  as  a rule,  it  should  be  avoided. 
When  exhausting,  a partial  vacuum  is  created  within  the  apartment,  and  all 
currents  and  leaks  are  inward  ; there  is  nothing  to  govern  definitely  the  quality 
and  place  of  introduction  of  the  air,  and  it  is  difficult  to  provide  proper  means 
for  warming  it.  Under  this  system  provision  is  often  made  for  drawing  the  air 
across  steam  pipes  placed  opposite  windows,  with  the  expectation  that  the  air  will 
become  thoroughly  heated  in  passing  across  them.  Such  oftens  fails  to  be  the 
case,  for  the  most  direct  course  is  taken  by  the  air  toward  the  existing  vacuity, 
and  only  a portion  of  the  heating  surface  is  utilized. 


18 


fMi  VENTILATION  and  HEAT1NG« 

THE  PLENUM  METHOD.  On  the  other  hand,  when  the  air  is  forced  in, 
its  quality,  temperature  and  point  of  admission  are  completely  under  control ; in 
a word,  the  method  is  positive;  all  spaces  are  tilled  with  air  under  a slight 
pressure,  and  the  leakage  is  outward,  preventing  the  drawing  of  polluted  air  into 
the  room  from  any  source.  But,  above  all,  ample  opportunity  is  given  for 
properly  tempering  the  air  by  means  of  heaters,  either  in  direct  communication 
with  the  fan  itself  or  in  separate  passages  leading  to  the  various  rooms. 

DETERMINATION  OF  HEATING  CAPACITY  REQUIRED.  The 
amount  of  heat  required  to  comfortably  warm  a given  space  is  dependent  upon 
many  variables.  Most  important  of  all  is  the  difference  in  temperature  between 
the  indoor  and  the  outdoor  air ; for  the  rate  of  passage  of  heat  through  walls  is 
practically  in  direct  proportion  to  the  difference  in  temperature  upon  the  opposite 
sides  of  the  wall.  The  material  of  such  walls,  of  course,  governs  the  rapidity  of 
this  loss ; — under  general  conditions,  wooden  buildings  most  rapidly  dissipate 
the  heat,  and  stone  next,  while  brick  buildings  best  retain  the  heat.  Obviously 
the  relative  area  of  window  surface  materially  affects  the  loss  of  heat,  while  the 
amount  of  wall  and  window  surface,  in  proportion  to  the  cubic  contents  of  the 
apartment;  the  climate,  the  location  (whether  high  or  low,  or  upon  the  side  of 
the  building  subject  to  the  most  chilling  winds),  and  the  method  of  heating, — 
all  have  an  influence.  With  so  many  modifying  considerations,  it  is  evident  that 
no  unalterable  rule  can  be  given  for  heating  all  classes  of  buildings,  but  that 
satisfactory  results  can  only  be  obtained  by  separate  calculation  for  each. 

From  the  known  heat-transmitting  power  of  various  forms  of  construction, 
the  loss  of  heat  may  be  determined  with  reasonable  accuracy.  The  conductivity 
of  such  surfaces  is  generally  expressed  in  the  number  units  of  heat  transmitted 
per  hour  per  square  foot  of  surface  for  each  degree  difference  between  the 
temperatures  of  its  two  sides.  The  entire  subject  has  been  very  carefully 
investigated  by  the  German  Government,  and  the  results  incorporated  in  a series 
of  coefficients — -representing  the  best  practice  — to  be  employed  in  determining 
the  relative  rates  of  transmission  for  various  substances  employed  in  construction. 
It  is  prescribed  by  law  that  these  coefficients  shall  be  applied  in  the  design  of  its 
public  buildings,  and  generally  used  in  Germany  for  all  buildings. 

These  values  have  been  transformed  into  American  units  by  Alfred  R. 
Wolff,  M.  E.,*  and  by  him  slightly  modified  to  suit  our  climatic  conditions.  The 
most  important  of  these  coefficients  — representing  the  heat  transmission  in 
units  per  hour  per  square  foot  of  surface  per  degree  difference  in  temperature  — 
are  here  presented : 

♦The  Heating-  of  Large  Buildings  : Alfred  R.  Wolff,  M.E.,  New  York. 

19 


VENTILATION  and  HEATING 


THE  COEFFICIENT  BEING  FOR  EACH  SQUARE  FOOT  OF  BRICK 

WALL,  OF  THICKNESS: 


Thickness  of  Brick  Wall,  in  Inches, 

4 

8 

12 

16 

20 

24 

28 

32 

36 

40 

Coefficient 

.458 

.315 

.258 

.228 

.194 

.165 

.143 

.129 

.114 

l square  foot,  wooden  beam  construction, ) as  flooring 083 

planked  over,  or  ceiled,  i as  ceiling 104 

1 square  foot,  fireproof  construction, ) as  flooring  ...  122 

floored  over,  J as  ceiling 145 

1 square  foot,  single  window 1.215 

1 square  foot,  single  skylight  . 1.03 

1 square  foot,  double  window 572 

l square  foot,  double  skylight  . 621 

1 square  foot,  vault  light 143 

l square  foot,  door  (65%  wood,  35%  glass) 572 

l square  foot,  door  (plain) 414 


It  is  further  prescribed  that  these  coefficients  are  to  be  increased  respectively 
as  follows : 

Ten  per  cent,  where  the  exposure  is  a northerly  one,  and  winds  are  to  be 
counted  on  as  important  factors. 

Ten  per  cent,  when  the  building  is  heated  during  the  daytime  only,  and  the 
location  of  the  building  is  not  an  exposed  one. 

Thirty  per  cent,  when  the  building  is  heated  during  the  daytime  only,  and 
the  location  of  the  building  is  exposed. 

Fifty  per  cent,  when  the  building  is  heated  during  the  winter  months  inter- 
mittently, with  long  intervals  (say  days  or  weeks)  of  non-heating. 

From  the  above,  Mr.  Wolff  has  also  prepared  a diagram,  in  form  similar 
to  that  here  given  (Fig.  2),  which  serves  to  present  the  data  graphically  in  the 
most  comprehensive  manner  for  practical  application. 

By  the  use  of  this  diagram  it  is  possible  to  determine  the  total  loss  of  heat 
by  transmission  from  a given  room,  and  to  thereby  ascertain  the  amount  of  heat, 
as  measured  in  heat  units,  that  must  be  continuously  supplied  to  the  room  to 
make  good  this  loss  and  maintain  the  temperature.  But  this  does  not  cover 
the  additional  heat  necessary  on  account  of  change  of  air  for  the  purposes  of 
ventilation. 


20 


DIFFERENCE  BETWEEN  INDOOR  AND  OUTDOOR  TEMPERATURE 

FIG.  2.  Heat  Transmitted,  in  British  Thermal  Units,  per 
Hour  per  Square  Foot  of  Surface. 

21 


VENTILATION  and  HEATING 


EFFECT  OF  VENTILATION  ON  HEATING.  The  reduction  of  tem- 
perature within  a building  is  the  result,  first,  of  the  combined  losses  of  heat  by 
conduction  through  and  radiation  from  windows,  doors,  walls,  floors  and  ceilings, 
as  has  been  pointed  out;  and,  second,  by  direct  leakage  or  escape  of  air  at  the 
temperature  of  the  room.  The  former  varies  directly  with  the  difference  between 
the  internal  and  the  external  temperatures,  and  is  proportional  thereto.  Wherever 
the  blower  system  is  used,  the  cost  of  heat  supply,  to  make  good  this  loss,  is 
measured  by  the  difference  between  the  average  temperature  of  the  air  within  the 
room  and  that  of  the  air  as  it  is  first  discharged  into  the  room  from  the  heating 
apparatus,  disregarding  losses  in  transit  from  the  apparatus. 

The  loss  by  leakage  and  escape  of  air  is  measured  directly  by  the  difference 
between  indoor  and  outdoor  temperatures,  this  representing  the  heat  added  to  the 
air,  which  serves  no  directly 'useful  purpose  in  heating.  It  is  thus  evident  that 
with  a constant  volume  of  air  the  expenditure  for  heating  will  be  indicated  by 
the  loss  by  the  first  method,  and  that  for  ventilation  by  the  loss  of  warm  air 
escaping  by  the  second  means. 

When  heating  alone,  as  the  ultimate  object  of  the  introduction  of  the 
Sturtevant  System,  is  considered,  it  will  be  found  that  to  maintain  a temperature 
of  70°  with  outdoor  temperature  at  zero,  a change  of  air  every  sixteen  minutes 
with  an  entering  temperature  of  about  140°  will  represent  a fair  average  in  the 
northern  portions  of  this  country.  Under  these  circumstances,  disregarding  the 
weight  or  density  of  the  air  at  different  temperatures,  the  difference  between  70° 
and  140°  will  represent  the  loss  by  radiation  and  conduction.  If  with  the  same 
entering  temperature  the  loss  is  greater,  the  temperature  of  the  room  will  be 
lower,  and  vice  versa.  There  is  thus  lost  tVs,  or  one-half,  of  all  the  heat  by  this 
means;  or  if,  for  ready  comparison,  we  represent  each  degree  as  a unit,  not  of 
heat  but  merely  of  relative  measurement,  there  will  have  been  lost  70  units.  If, 
in  a given  time,  a given  volume  of  air  is  delivered  to  the  room,  its  cost  in  total 
heat  expenditure  must  be  measured  by  the  number  of  degrees  its  temperature 
has  been  raised  above  zero ; that  is,  upon  our  basis  of  comparison,  it  will  be 
equivalent  to  140  units. 

In  the  given  time  all  of  this  air  must  escape  at  the  temperature  of  the  room, 
which  is  here  70°  ; hence  the  loss  by  this  means  will  also  be  70  units,  and  it  can 
bv  no  means  be  reduced  except  by  deliberately  decreasing  the  volume  of  air 
admitted,  or  by  increasing  the  difference  between  internal  and  external  tempera- 
tures. It  is  evident  that  with  a fan  running  at  constant  speed  and  delivering  a 
stated  volume  of  air,  the  ventilation  may  be  reduced  by  returning  a portion  of 
the  air  from  the  building,  and  the  expenditure  likewise  lessened.  The  loss  by 


22 


VENTILATION  and  HEATING 


radiation  and  conduction,  on  the  other  hand,  can  be  reduced  by  sufficient,  although 
perhaps  extravagant,  expenditure  for  double  or  triple  sash,  thicker  walls,  back 
plaster,  sheathing  paper,  and  the  like. 

If,  with  the  same  air  change,  all  the  air  should  be  returned  from  the  building 
on  the  impossible  assumption  that  there  is  no  leakage,  the  temperature  of  the 
air  admitted  would  still  require  to  be  140°,  and  the  loss  by  radiation  and  conduc- 
tion would  be  the  same,  namely  70  units,  but  the  leakage  would  be  reduced  to 
zero,  and  the  total  heat  expenditure  would  be  only  one-half  of  that  in  the  former 
instance. 

If,  now,  under  the  same  conditions  of  construction  the  building  be  fully  occu- 
pied and  the  demands  of  ventilation  be  considered,  it  will  be  necessary  to  reduce 
the  time  of  air  change,  i.e.,  increase  the  volume  of  air  delivered.  If  the  building 
be  occupied  as  a school,  with  the  ordinary  ratio  of  about  250  cubic  feet  of  room- 
space  per  pupil,  it  will  be  necessary,  in  order  to  supply  30  cubic  feet  of  air  per 
minute  per  pupil,  to  furnish  a volume  equivalent  to  changing  the  air  once  in 
about  eight  minutes. 

With  outdoor  air  still  at  zero  and  an  indoor  temperature  to  be  maintained  at 
70°,  it  is  evident  that  with  the  air  supply  just  double  that  in  the  first  instance  (as 
would  be  true  with  the  eight-minute  change),  its  temperature  need  not  be  as  high  ; 
in  fact,  as  the  real  heating  power  of  the  admitted  air  is  measured  only  by  its 
temperature  above  70°,  which  was  140  — 70  = 70°  in  the  former  instance,  there 
will  now  be  required,  with  double  the  air  volume,  only  one-half  the  temperature 
increment,  or  3 5°. 

Compared  by  units,  it  will,  therefore,  be  necessary  to  provide  for  the  loss 
by  leakage  twice  as  many  as  before,  that  is,  2 X 70=  140.  To  these  must  be 
added  those  supplied  for  radiation  and  conduction,  which,  with  twice  the  volume 
of  air  and  an  increment  of  35°,  will  still  equal  70  units,  or  a total  of  140 -j—  70 
= 210  units.  But  as  the  volume  is  double,  its  temperature,  volume  for  volume, 
as  compared  with  the  first  illustration,  will  be  210-y2  = 105°,  which  evidently 
equals  70  + 35  degrees. 

To  summarize,  there  will  now  be  required  210  units  as  against  140  units  in 
the  first  instance,  an  increase  of  50  per  cent.,  and  three  times  as  many  as  under 
the  assumed  condition  of  all  return  air  to  the  apparatus,  — while  the  temperature 
of  the  admitted  air  stands  at  140°  for  the  sixteen-minute  and  105°  for  the  eight- 
minute  change. 

These  propositions  are  more  clearly  presented  in  the  accompanying  diagram, 
Fig.  3,  of  the  cost  of  heating  and  ventilation,  with  the  relative  cost  of  heating 
alone,  and  of  temperatures  of  entering  air.  Of  course,  it  is  impossible  to  make 


23 


M VENTILATION  and  HEATING  M 


2 4 6 8 10  12  14  16  18  20 

DAVE  OF  CHANGING  AIR . IN /AINUTES 


FIG.  T Relative  Costs  of  Heating  and  Ventilation, 
with  Different  Temperatures  of  Entering  Air. 


24 


Units 


VENTILATION  and  HEATING 


this  accurately  applicable  to  all  classes  of  buildings,  as  the  lines  are  based  upon  the 
proportions  previously  given,  which  can  only  be  said  to  represent  a fair  average. 
They  do  make  clear,  however,  the  approximate  relations  existing  between  the 
cost  of  heating  (which  is  constant)  and  the  cost  of  ventilation  (which  increases 
with  the  volume  of  air  admitted),  and  serve  to  make  evident  the  necessity  of 
increased  boiler  capacity  where  improved  ventilation  is  introduced.  As  here 
represented,  the  individual  cost  of  ventilation  is  additional  to  that  for  heating, 
and  is  to  be  measured  above  the  line  of  cost  for  heating.  The  relative  cost  for 
both  heating  and  ventilation  combined  is  to  be  measured  from  the  base  line. 


HEATING  CALCULATIONS.  The  thermal  value,  or  heating  power,  of 
water  and  of  steam  has  been  found  by  elaborate  experiments,  and  the  results  are 
embodied  in  complete  and  convenient  tables.  By  a proper  understanding  and 
use  of  such  tables,  in  connection  with  tables  of  the  properties  of  air,  ready 
calculations  may  be  made  in  all  matters  relating  to  steam  heating.  The  following 
tables,  No.  2,  Of  the  Properties  of  Saturated  Steam,  and  No.  3,  Of  the  Number 
of  Thermal  Units  Contained  in  One  Pound  of  Water,  embody  the  principal 
data.  Table  No.  1,  Of  the  Properties  of  Air,  Vapor  and  Saturated  Mixtures  of 
Air  and  Vapor,  has  already  been  presented.  Figures  between  those  given  in 
the  tables  may  be  obtained  with  sufficient  accuracy  by  interpolation. 

It  is  customary  to  base  calculations  of  heating  capacity  upon  the  number  of 
pounds  or  cubic  feet  of  air  that  can  be  heated  by  the  condensation  of  one  pound 
of  steam.  The  specific  heat  of  air  under  constant  pressure  is  .2379  compared 
with  water  as  a standard.  That  is  to  say,  the  heat-absorbing  power  of  air  is 
about  one-fourth  that  of  water,  and  the  amount  of  heat  required  to  heat  one 
pound  of  water  through  1°  F,  will  heat  .2^=4.2034  pounds  of  air,  through  the 
same  increment.  The  total  heat  and  sensible  temperature  of  steam  increase  with 
the  pressure,  as  seen  by  Table  No.  2.  Upon  condensation,  steam  gives  up  its 
latent  heat  and  is  resolved  into  water  having  the  same  temperature  as  the  steam 
from  which  it  was  condensed.  Hence,  the  heating  power  of  a pound  of  steam 
of  a given  pressure  is  expressed  by  the  heat  thus  given  out,  i.e.,  by  the  total 
number  of  units  of  heat  in  the  original  steam  less  the  number  in  the  final  water 
of  condensation. 

Taking  a pressure  of  86  pounds  above  vacuum,  for  instance,  the  temperature 
of  the  steam,  as  well  as  that  of  the  water  from  which  it  was  evaporated,  is 
316.84°,  while  the  total  heat  in  the  steam,  as  measured  in  heat  units,  is  1,210.58 
units  (by  column  4,  Table  No.  2).  The  890.69  units  of  heat  (column  3)  which 
were  added  to  each  pound  of  water  of  3 16.84°  temperature  to  evaporate  it  into 


25 


» VENTILATION  and  HEATING  « 


TABLE  No.  2. 

Of  the  Properties  of  Saturated  Steam. 


Total  Pressure 

Temperature  in 
Degrees  Fahrenheit 
ot  Steam  and  of  the 
Water  from  which 
it  was  evaporated. 

.Number  of  British  Thermal  Units  contained  in 
one  pound,  reckoned  from  Zero  Fahrenheit. 

Weight  of 
one  Cubio  Foot  of 
Steam  in  decimals 
of  a pound. 

Relative  Volume 

per  square  inch, 
measured  from 
a Vacuum 

Number  required  for 
evaporation,  known  os 
latent  heat,  or  heat 
of  vaporiaation. 

Total  number 
oontaincd  n the 
Steam. 

Volume  of 
one  pound  of  bteam 
m Cubio  Feet. 

or  Cubic  Peel  of 
Steam  from  one 
Cubic  1 oot  ot 
Water. 

1 

2 

3 

4 

5 

6 

7 

1 

102. 

1042.96 

1145-05 

.0030 

330-36 

20620. 

2 

126.27 

1026.01 

1152-45 

.0058 

172.08 

10720. 

3 

141.62 

1015.25 

ii57-i3 

.00S5 

I17-52 

7326. 

4 

15307 

1007.23 

1 160.62 

0112 

89.62 

5600. 

5 

162.33 

1000.73 

1163-45 

•0137 

72.66 

4535- 

6 

170.12 

995-25 

1165.83 

•0163 

61.21 

3814- 

7 

176.91 

990.47 

1 167.90 

.0189 

52-94 

33oo. 

8 

182.91 

986.25 

1169.73 

.0214 

46.69 

2910. 

9 

iss.32 

982-43 

ii7i-37 

•0239 

4i-79 

2607. 

10 

193- 24 

978.96 

1172. S8 

.0264 

37-84 

2360 

12 

201.96 

972.80 

U75-54 

•0313 

3i-95 

1988. 

14 

209.56 

967  43 

1177-85 

.0361 

27-63 

1722. 

14.7 

212. 

965  7 

1 178.60 

.0380 

26.36 

1644. 

16 

216.30 

962.66 

ii79-9‘ 

.0413 

24.21 

I5H- 

18 

222.38 

958-34 

1181.76 

.0462 

21.64 

13506 

20 

227.92 

954-41 

IO 

-t- 

ro 

CO 

•0511 

19-57 

1220.3 

22 

233-02 

950-79 

1 185.01 

■0561 

17-83 

IU3-5 

24 

237-75 

947-42 

1186.45 

.0610 

16.39 

1024.  I 

26 

242.17 

944.28 

1187.80 

.0658 

1519 

948.4 

28 

246-33 

941-32 

1189.07 

.0707 

14.14 

883.2 

30 

250.24 

938.92 

1 190. 26 

•0755 

13-25 

826.8 

32 

253-95 

935-88 

1191-39 

.0803 

12-45 

777-2 

34 

257-48 

933-37 

1192.47 

.0851 

ii-75 

733-5 

36 

260.S3 

930-97 

1193-49 

.0899 

II. II 

694-5 

38 

264.05 

928.67 

1194.47 

.0946 

10.56 

659-7 

40 

267.12 

926.47 

1 195.41 

.0994 

10.06 

628.2 

42 

270.07 

924-36 

1196.31 

.1041 

9 59 

599-3 

44 

272.91 

922.32 

1197.18 

.1088 

9. 18 

573-7 

46 

275-65 

920.36 

1198.01 

•1134 

8.82 

5.50-4 

48 

27S.30 

9*8-47 

119S.82 

.1181 

8.47 

529.0 

50 

280.85 

916.63 

1199.60 

.1227 

8.15 

508.5 

52 

283  33 

914.86 

1200.35 

.1274 

7-85 

490.1 

54 

285.72 

913- 13 

1201.09 

.1320 

7-58 

472.9 

56 

288.05 

911.46 

1201.80 

•1366 

7-32 

457-o 

58 

290.32 

90983 

1202.49 

.I4II 

7.08 

442.4 

26 


M VENTILATION  and  HEATING  M 


TABLE  No.  2. 

Of  the  Properties  of  Saturated  Steam. — Continued. 


1 

‘A 

3 

4 

5 

a 

7 

60 

292.52 

9°S.25 

1203. 16 

•'457 

6.86 

428.5 

62 

294.66 

906.70 

1203. Si 

.1502 

6.66 

415.6 

64 

296-75 

905.20 

1204.45 

•'547 

6.46 

403-5 

66 

29S.79 

9°3-73 

1205.07 

•1592 

6.28 

392-1 

68 

300. 7S 

902 . 30 

1205. 6S 

■1637 

6. 10 

3S1.3 

70 

302.72 

9OO.9O 

1206.27 

.16S2 

5-95 

371-2 

72 

304.62 

S99- 53 

1206.85 

.1726 

5. So 

36i-7 

74 

306-47 

S9S.  19 

1207.41 

.1770 

5-65 

352-6 

76 

30S.29 

S96.SS 

1207.97 

.1S14 

5-5' 

344-' 

78 

310.07 

§95-59 

1208.51 

.1858 

5-34 

336-o 

80 

31 1. Si 

§94-33 

I2O9.O4 

. 1901 

5.26 

328.3 

82 

313-5- 

S93.09 

1209.56 

•'945 

5- '4 

320.9 

84 

3I5-I9 

891. 8S 

1210.07 

.1989 

5-03 

3'3-9 

86 

316.S4 

890.69 

1210.5S 

•2032 

4-92 

307.2 

88 

3iS.45 

SS9.52 

12  I I.07 

•2075 

4.S2 

300.8 

90 

320.04 

CO 

ro 

CO 

CO 

CO 

'2H-55 

.2118 

4-72 

294-7 

92 

321.60 

SS7-25 

1212.03 

.2161 

4-63 

28S.9 

94 

3-3- 13 

8S6.I4 

1212.49 

.2204 

4-54 

283-3 

96 

3-4-63 

SS5.04 

1212.95 

•2245 

4.44 

278.0 

98 

326.11 

SS3.97 

1213.40 

.2288 

4-37 

272.8 

100 

3-7-57 

8S2.9I 

1213.85 

•2330 

4.29 

267.9 

105 

331-11 

8S0.34 

1214.93 

•2434 

4. 1 1 

256-5 

110 

33452 

S77.S6 

1215-97 

•2538 

3-94 

246.0 

115 

337-Si 

§75-47 

1216.97 

.2640 

3-79 

236-3 

120 

340-99 

§73-15 

1217.94 

--743 

3-65 

227.6 

125 

344-oy 

870.90 

I2IS.SS 

•2843 

3-52 

219.7 

130 

347-06 

S6S.73 

1219.79 

•2942 

3-40 

212.3 

135 

349-95 

866.62 

1220.68 

•3040 

3-29 

205-4 

140 

35— -77 

864.57 

1221.53 

•3139 

3-  '9 

199.0 

145 

355-5° 

862.57 

1222.37 

•3239 

3 09 

193.0 

150 

35S-i6 

S60.62 

1223.18 

•3340 

2.99 

287-5 

160 

363-2S 

856.87 

1224.74 

•3521 

2.84 

'77-3 

170 

368.16 

§53-29 

1226.23 

■3709 

2.69 

16S.4 

180 

372.S2 

S49.S7 

1227.65 

•3SS9 

2*57 

160.5 

190 

377-29 

S46.5S 

1229.01 

.4072 

2-45 

'53-4 

200 

3Si-57 

§43-43 

1230.32 

•4250 

2-35 

147. 1 

250 

401.07 

§31-22 

1235-73 

•5464 

1.S3 

114. 

300 

41S.22 

S19.61 

1240.74 

.6486 

'-54 

96. 

350 

431.96 

S10.69 

1244.58 

•7498 

'•33 

S3- 

400 

444-92 

S00.20 

1249.09 

• S>02 

1. 18 

73- 

a VENTILATION  and  HEATING 


TABLE  No.  T 

Of  the  Number  of  Thermal  Units  Contained  in  One 

Pound  of  Water. 


Temperature. 

Number  of 

Thermal  Units 

Increase. 

Temperature. 

Number  of 
Thermal  Units. 

Increase. 

Temperature. 

Number  of 

Thermal  Units. 

Increase. 

35 1 

35.00° 

155° 

I55-339 

5 034 

275° 

276.985 

5-107 

40 

40.001 

5-001 

160 

i6o-374 

5-°35 

280 

282.095 

5-no 

45 

45.002 

5.001 

165 

165.413 

5-039 

285 

2S7.210 

5-115 

50 

50.003 

5.OOI 

170 

i7o-453 

5 -04°. 

290 

292.329 

5-H9 

55 

55.006 

5 -003 

175 

175-497 

5-044 

295 

297-452 

5-123 

60 

60.009 

5-003 

180 

180.542 

5-045 

300 

302. 5S0 

5.128 

65 

65.014 

5-005 

185 

1S5.591 

5-049 

305 

307.712 

5-I32 

70 

70.020 

5.006 

190 

190.643 

5-052 

310 

312.848 

5-i36 

75 

75-°-7 

5.007 

195 

195.697 

5-054 

315 

317.9SS 

5140 

80 

So  .036 

5.OO9 

200 

200.753 

5-056 

320 

323-134 

5-146 

85 

85-045 

5.009 

205 

205.813 

5 060 

325 

328.284 

5-150 

90 

90055 

5.01° 

210 

210.874 

5.061 

330 

• 

333-438 

5-254 

95 

95.067 

5.012 

215 

215-939 

5-065 

335 

338-596 

5-'58 

100 

100.0S0 

5 °>3 

220 

221.007 

5.068 

340 

343-759 

5-163 

105 

105.095 

5-OI5 

225 

226.07S 

5-071 

345 

34S-927 

5.168 

110 

I IO.  I IO 

5-OI5 

230 

231-153 

5-?75 

350 

354-ioi 

5-174 

115 

115. 129 

5.019 

235 

236.232 

5-°79 

355 

359.280 

5-179 

120 

I 20. 1 49 

5.020 

240 

241-313 

5.081 

360 

364.464 

5-284 

125 

125.169 

5.020 

245 

246-398 

S-o85 

365 

369-653 

5.189 

130 

130.192 

5 -°-3 

250 

251.487 

5.0S9 

370 

374-846 

5-193 

135 

1 3 5 - - 1 7 

5-0^5 

255 

256-579 

5.092 

375 

380.044 

5.198 

140 

140.245 

5.028 

260 

261.674 

5-095 

380 

385-247 

5 203 

145 

145-175 

5.030 

265 

266.774 

5.100 

385 

390-456 

5.209 

150 

150-305 

5-030 

270 

271-878 

5-i°4 

390 

395-672 

5.216 

28 


VENTILATION  and  HEATING 


15?AQ 


steam  will,  upon  the  condensation  of  that  steam,  reappear  as  available  for  heat- 
ing. The  standard  unit  of  heat  is  equivalent  to  the  amount  of  heat  necessary  to 
raise  the  temperature  of  one  pound  of  water  through  one  degree  Fahrenheit  at 
its  point  of  greatest  density.  A heat  unit  is  not  to  be  confounded  with  a degree 
of  temperature,  notwithstanding  the  fact  the  visible  temperature  of  water,  as 
expressed  in  degrees,  and  the  total  heat,  as  stated  in  heat  units,  are  indicated  by 
very  nearly  the  same  figures  (see  Table  No.  3),  the  variation  being  due  to  the 
altered  density  of  the  water. 

If,  therefore,  one  heat  unit  will  raise  the  temperature  of  one  pound  of  water 
through  one  degree  under  stated  conditions,  890.69  units  — given  out  by  the 
condensation  of  one  pound  of  steam  of  86  pounds  pressure  — will  heat  890.69 
pounds  of  water  through  one  degree.  Allowing  for  the  difference  in  specific 
heat,  this  same  heat  expenditure  would  result  in  raising  the  temperature  of 
890.69X4.2034  = 3,743.926  pounds  of  air  through  one  degree.  Supposing  the 
air  to  be  originally  at  a temperature  of  320,  then,  if  dry,  its  weight  per  cubic  foot 
would  be  .0807  pounds  (column  3,  Table  No.  1),  and  3,743-926  pounds  would  be 
equivalent  to  ijTf = 46,393  cubic  feet.  Upon  this  basis  Table  No.  4 has  been 
calculated,  it  being  assumed  that  the  water  of  condensation  is  not  cooled  below 
the  temperature  of  the  steam  from  which  it  is  condensed.  The  amount  of  heat 
that  would  thus  increase  the  temperature  of  the  volume  of  air  through  one 
degree  would  raise  the  temperature  of  half  the  amount  through  twice  as  many 
degrees,  and  so  on  in  like  proportion,  so  far  as  the  unitial  difference  between  the 
temperature  of  the  air  and  of  the  steam  will  permit. 

As  an  illustration  of  the  application  of  Table  No.  4,  suppose  it  is  desired  to 
heat  500,000  cubic  feet  of  dry  air  from  320  to  92°,  or  through  an  increment 
of.60°,  with  steam  of  75  pounds  absolute  pressure.  By  Table  No.  4 it  is  seen 
that  one  pound  of  steam  at  the  given  pressure  will  raise  46,736  cubic  feet  of  air 
at  32°  through  one  degree,  and  consequently  iW“  = 778.93  cubic  feet  through 
60°.  To  heat  500,000  cubic  feet  through  60°  there  will,  therefore,  be  required 
= 641.9  pounds  of  steam.  Of  course,  it  must  be  evident  from  the  preced- 
ing that  calculation  has  only  been  made  of  the  amount  of  heat  directly  applied 
for  heating.  If  the  water  of  condensation  can  be  returned  to  the  boiler  without 
material  reduction  of  temperature,  there  need  be  but  little  loss  in  this  direction ; 
but  where  it  is  thrown  away,  as  is  frequently  the  case  with  exhaust  steam,  the 
total  heat  expenditure  for  producing  the  steam  from  the  feed  water  at  its  initial 
temperature  must  be  made  the  basis  of  calculation.  The  horizontal  column  at 
the  bottom  of  the  table  indicates  that  the  presence  of  vapor  in  the  air,  even  to 
saturation,  has  but  slight  effect  upon  the  values  at  low  or  moderate  temperatures. 


29 


VENTILATION  and  HEATING 


TABLE  No.  4. 

Of  the  Number  of  Cubic  Feet  of  Dry  Air  that  may  be 
Heated  through  f (F.)  by  the  Condensation 
of  One  Pound  of  Steam. 


INITIAL  TEMPERATURE  OF  AIR. 

Steam  Pressure 


above  Vacuum. 

0 

123 

22> 

32 

42  a 

52J 

62 J 

72° 

82° 

92° 

102° 

15  46,946 

48.173 

49.225 

50,262 

51,279 

52,270 

53,300 

54,299 

55,343 

56,336 

57,371 

25  46,014 

47,217 

48.249 

49,265 

50.262 

5L233 

52,243 

53,222 

54,239 

55-2’S 

56,233 

3 5 45.349 

46.535 

47-55’ 

4S.553 

49-535 

50,492 

51,48s 

52,452 

53-454 

54-4’9 

55,420 

45  44.823 

45.994 

46,999 

47-9S9 

4S.834 

49,907 

50,890 

5’,844 

52,834 

53,788 

54-777 

5 5 44. 391 

45,55’ 

46,546 

47 .527 

48«4SS 

49-4’ 3 

50,399 

51,344 

52,325 

53,270 

54,248 

65  44.002 

45. ’4° 

46,139 

47,110 

48,064 

4S.993 

49,956 

50,907 

51,866 

52,831 

53-774 

75  43-665 

44,So6 

45785 

46,746 

47,695 

4S,6i6 

49-575 

50,504 

51,469 

52,399 

53.362 

85  43,361 

44-493 

45.466 

46,424 

47,36i 

48,279 

49,230 

50,153 

51,111 

52,034 

52,990 

95  43.084 

44.209 

45-176 

46,127 

47,060 

47,969 

48,905 

49-S32 

50,784 

5i,7oi 

52,652 

105  4-.S29 

43.972 

44'9°S 

45,854 

46,780 

47-6S4 

48,626 

49,538 

50,485 

5 ’,395 

52-339 

Per  ct.  of  above 
amounts  that 
will  be  heated  99*^ 
i°  if  air  is  satu- 
rated. 

99  6 

99-4 

99° 

9S.6 

9S.0 

97.1 

96.0 

94-5 

92-5 

90.  I 

From  a knowledge  of  the  number  of  units  of  heat  required,  or  the  total 
weight  of  steam  necessary  per  unit  of  time  for  any  given  building,  it  is  a simple 
matter  to  deduce  the  size  and  capacity  of  the  boiler  to  be  provided.  A proper 
understanding  of  the  relative  values  of  high  and  low  pressure  steam  will  result 
in  due  consideration  being  given  to  this  factor  in  deciding  upon  the  boiler 
capacity. 

EFFICIENCY  OF  HEATING  SURFACE.  The  character  and  efficiency 
of  the  heating  surface  does  not  enter  into  such  calculations  as  have  just  been 
described.  The  number  of  heat  units  necessary  to  be  transmitted  to  the  air  in  a 
given  time  being  known,  it  rests  with  the  designer  to  determine  the  amount  and 
arrangement  of  heating  surface  to  be  provided  to  secure  the  desired  results. 
Obviously,  the  higher  the  efficiency  of  such  surface,  i.e.,  the  greater  the  number 


30 


VENTILATION  and  HEATING 


of  pounds  of  steam  that  may  be  condensed  per  hour  per  square  foot  of  heating- 
surface,  the  smaller  and,  other  things  being  equal,  the  less  expensive  that  surface 
will  be.  The  efficiency  of  any  heating  surface  must  be  directly  dependent,  first, 
upon  its  character  and  arrangement,  and,  second,  upon  the  volume  of  air  passing 
across  it.  Under  the  conditions  of  an  open-pipe  radiator  with  air  surrounding 
it  at  an  average  temperature  of  60°,  Robert  Briggs  gives,  as  the  factor  accepted 
by  him,  a loss  of  1.8  units  per  hour  per  square  foot  of  heating  surface  per  degree 
difference  of  temperature  between  the  steam  inside  and  the  air  outside.  Other 
writers  and  investigators  give  somewhat  varying  values.  Taking  the  air  tem- 
perature at  60°  and  the  temperature  of  exhaust  steam  at  216°  (nearly),  the 
difference  would  be  156°,  and  the  number  of  units  given  out  per  hour  per  square 
foot  of  heating  surface  would  be  156X  1.8  = 280.8  units.  The  latent  heat  of 
steam  at  atmospheric  pressure  is  965.7  (column  ),  Table  No.  2),  therefore, 
IS?:?  = .29  pounds  of  steam  would  be  condensed  per  hour  per  square  foot  of 
heating  surface.  A similar  calculation  gives  .44  pounds  with  steam  at  70  pounds 
gauge  pressure.  Direct  experiments  made  at  the  works  of  this  Company,  on  a 
series  of  pipes  exposed  to  air  of  about  60°  and  strung  around  a room  at  about 
three  inches  from  a cold  brick  wall,  showed  a condensation  somewhat  greater 
than  this,  but  probably  due  to  several  modifying  influences,  particularly  that  of 
the  cold  wall. 

Under  such  an  arrangement  a large  proportion  of  the  heat  is  given  up  by 
radiation  to  the  air  and  surrounding  objects,  the  remainder  being  conducted 
directly  to  the  air  which  passes  across  the  surface.  These  two  means  exist  as  the 
opportunities  for  the  communication  of  heat  — convection,  so-called,  being  only 
a form  of  conduction.  Radiation  takes  place  in  straight  lines,  so  that  a given 
amount  of  surface  becomes  less  efficient  as  a radiator , as  it  is  massed  in  such 
form  as  to  interfere  with  the  radiation  of  heat  directly  to  the  surrounding  objects. 
Air  is  a very  poor  absorber  of  radiant  heat,  so  that  it  is  evident  that  the  effi- 
ciency of  a massed  coil  can  only  be  increased  by  giving  it  greater  opportunity 
for  conduction  of  heat  from  its  surface  to  the  air  with  which  it  is  in  contact.  In 
other  words,  by  increasing  the  air  flow  across  this  surface  in  such  a way  that  the 
heat  may  be  almost  literally  wiped  off  and  carried  to  a point  where  the  air  may 
advantageously  part  with  it. 

Upon  this  principle  the  hot-blast  apparatus  is  designed  and  its  high  efficiency 
secured.  Many  factors  enter  to  determine  the  form,  proportions  and  general 
arrangement  of  the  heating  surface,  as  well  as  the  permissible  air  volume,  in  such 
an  apparatus.  Appreciating  the  necessity  of  the  most  reliable  data,  and  knowing 
that  nothing  of  the  kind  existed,  this  Company  conducted  an  exhaustive  series 


VENTILATION  and  HEATING 


of  experiments,  covering  several  winter  months,  upon  various  forms  of  specially  - 
constructed  apparatus,  to  obtain  all  necessary  data  for  the  correct  design  and 
construction  of  its  apparatus,  as  well  as  the  intelligent  application  of  the  same. 
By  means  of  formulae  derived  from  these  experiments,  we  are  enabled  to  make 
most  accurate  determinations  of  resulting  temperatures  and  steam  condensation 
under  given  conditions,  as  well  as  to  design  new  work  with  the  most  positive 
assurance  of  success. 

Among  other  results  it  was  shown  that  in  the  Sturtevant  Heaters  a con- 
densation was  ordinarily  obtained  of  2 to  2\  pounds  of  high-pressure  steam  per 
hour  per  square  foot  of  heating  surface.  Of  course,  the  amount  of  condensa- 
tion is  dependent  upon  numerous  variables, — the  steam  pressure,  the  specific 
arrangement  of  the  heating  surface,  the  initial  temperature  and  the  velocity  of 
the  air.  Compared  with  the  previous  figures  upon  direct  radiation,  the  enormous 
gain  in  efficiency  is  evident.  A conservative  estimate  would,  therefore,  indicate 
the  Sturtevant  Heater  to  be  at  least  three  to  five  times  more  efficient  than  an 
open-pipe  radiator. 


HEATING  SURFACE  REQUIRED.  The  total  amount  of  heat  necessary, 
as  measured  in  heat  units,  having  been  determined  by  calculation  and  the  effi- 
ciency of  the  selected  form  of  heating  surface  being  known,  it  is  a comparatively 
simple  matter  to  decide  upon  the  amount  of  heating  surface  required  for  any 
given  building.  But  all  the  conditions  must  be  taken  into  consideration;  the 
calculations  must  be  made  for  the  minimum  winter  temperature,  the  steam 
pressure  must  be  known,  and  it  must  be  decided  whether  the  air  is  to  be  taken 
entirely  from  out-of-doors  to  the  heating  apparatus,  or  to  some  extent  returned 
from  the  building.  As  already  shown,  this  latter  practice  is  conducive  to 
economy,  but,  of  course,  is  not  to  be  employed  except  where  heating  is  the 
primary  object  in  the  introduction  of  the  system,  or  the  normal  supply  of  air  is 
very  large  per  capita. 

While  quantity  of  heating'  surface  is  of  the  utmost  importance,  its  arrange- 
ment is  hardly  less  important.  It  is  not  enough  to  have  a given  number  of 

lineal  feet  of  steam  coils,  or  pipes  spaced  a given  distance  on  centres,  but  it  is 

further  necessary  to  have  the  sections  or  groups  of  pipes  combined  in  such  form 
that  there  may  be  sufficient  free  area  between  the  pipes  to  allow  of  the  ready 
passage  of  the  air  handled  by  the  fan,  while  the  total  number  of  pipes  with 
which  a given  particle  of  air  comes  in  contact  in  its  passage  through  the  heater 
must  be  such  as  to  secure  the  requisite  rise  in  temperature  of  that  air.  Those 

who  do  not  possess  extended  experience  in  such  matters  are  very  apt  to  so 


32 


Hi  VENTILATION  and  HEATING« 

arrange  their  heating  surface  as  to  greatly  reduce  its  efficiency,  with  resulting- 
failure  in  the  heating  of  the  building  in  which  it  is  installed. 

One  of  the  important  objects  in  view  in  conducting  the  tests  on  Sturtevant 
Heaters,  previously  alluded  to,  was  to  determine  definitely  the  influence  of  dif- 
ferent arrangements  of  heating  surface  of  the  same  general  character  and  to 
ascertain  the  form  in  which  it  could  be  rendered  most  efficient.  In  other  words, 
to  place  this  Company  in  a position  to  specify  with  certainty  of  the  results  to  be 
accomplished,  the  most  economical  arrangement  of  the  heating  surface,  thereby 
decreasing  the  first  cost  of  the  apparatus  without  impairing  or  affecting  its 
efficiency. 

It  is  obviously  impossible  to  give  in  practical  form  all  of  the  data  thus 
obtained,  but  a statement  of  the  general  practice,  as  it  now  obtains,  may  at  least 
guide  somewhat  in  the  rough  planning  of  heating  and  ventilating  systems,  and 
serve  reasonably  well  as  a check  upon  calculations  made  by  the  methods  already 
described. 

In  hot-blast  heating,  the  proportional  heating  surface  is  generally  expressed 
in  the  number  of  net  cubic  feet  in  the  building  for  each  lineal  foot  of  one  inch 
steam  pipe  in  the  heater.  On  this  basis,  in  factory  practice,  with  all  of  the  air 
taken  from  out-of-doors,  there  is  generally  allowed  from  100  to  150  cubic  feet 
of  space  per  foot  of  pipe,  according  as  exhaust  or  live  steam  is  used,  the  term 
“live  steam”  being  taken  in  its  ordinary  sense  as  indicating  steam  of  about  80 
pounds  pressure.  If  practically  all  of  the  air  is  returned  from  the  building,  these 
figures  will  be  raised  to  about  140,  as  the  minimum,  and  possibly  200  cubic  feet, 
as  the  maximum,  per  foot  of  pipe.  Of  course,  the  larger  the  building  in  cubic 
contents  the  less  its  wall  and  roof  exposure  per  foot  of  cubic  space,  and  con- 
sequently the  less  the  loss  of  heat  and  the  smaller  the  heater  relatively  to  the 
cubic  contents.  In  such  buildings,  used  for  manufacturing  purposes,  where  the 
occupants  are  usually  well  scattered,  an  air  change  once  in  fifteen  to  twenty 
minutes  represents  the  general  practice,  but  in  public  and  similar  buildings  this 
change  is  of  necessity  reduced  to  once  in  seven  to  twelve  minutes.  Owing  to 
the  increased  loss  of  heat  by  leakage  or  ventilation  under  such  conditions,  and 
also  to  the  demand  for  a slightly  higher  temperature  than  in  the  shop,  the  allow- 
ance is  dropped  to  from  70  or  75  to  125  cubic  feet  of  space  per  foot  of  pipe, 
for  all  of  the  air  is  taken  from  out-of-doors  and  low-pressure  steam  is  usually 
employed.  The  great  range  in  all  of  these  figures  must  make  evident  the  influence 
of  the  size,  construction  and  uses  of  a building  upon  the  size  of  the  apparatus 
required,  and  show  the  necessity  of  extended  experience  for  the  proper  designing 
of  any  system  of  heating  and  ventilation. 

33 


VENTILATION  and  HEATING 


VALUE  OF  EXHAUST  STEAM.  Most  important  to  every  manufacturer 
is  the  complete  utilization  of  his  exhaust  steam,  for  it  usually  has  a value  as  a 
heating  medium  of  very  nearly  97  per  cent,  of  ordinary  high-pressure  steam. 
It  is  obviously  unwise  to  employ  live  steam  for  heating  when  exhaust  steam  is  at 
hand  or  even  at  some  distance,  for  the  expenditure  for  the  conducting  pipe  for 
such  waste  steam  will  almost  always  be  warranted. 

In  many  systems  of  direct  radiation  it  is  more  or  less  difficult  to  make  use 
of  the  exhaust,  but  the  Sturtevant  Heater  has  been  designed  with  this  special 
purpose  in  view.  It  is,  furthermore,  arranged  with  one  or  more  special  sections, 
in  which  may  be  condensed  the  exhaust  steam  from  the  small  engine  which  is 
usually  provided  for  driving  the  fan. 

Although  the  total  heat  (measured  in  heat  units)  of  exhaust  steam  and  of 
live  steam  of  80  pounds  is  very  nearly  the  same,  the  difference  in  actual  tem- 
perature is  such  — exhaust  steam  averaging  about  220°,  while  steam  of  80 
pounds  is  about  323° — that  there  is  a marked  difference  in  the  rate  at  which 
they  give  up  their  heat  when  enclosed  in  steam  pipes  across  which  air  is  caused 
to  circulate.  This  rate  of  transmission  is  proportional  to  the  difference  in  tem- 
perature between  the  steam  within  and  the  air  outside  the  pipe,  and,  therefore, 
exhaust  steam  requires  for  the  condensation  of  a given  weight  of  steam  in  a unit 
of  time  a larger  area  of  surface  than  live  steam. 

Furthermore,  exhaust  steam  being  less  dense  than  live,  it  must  require  a 
larger  pipe  to  convey  the  same  weight.  The  proper  proportioning  of  the  areas 
of  steam-conducting  pipes,  according  to  the  pressure,  seldom  receives  sufficient 
attention.  The  accompanying  table,  No.  5,  is  therefore  presented  to  show  the 
amount  of  steam  of  given  pressure  that  will  flow  per  minute  through  pipes  of 
various  sizes  with  a loss  of  only  one  pound  of  pressure.  From  this  may  be 
easily  determined  with  sufficient  accuracy,  the  size  of  steam  pipe  required  to 
conduct  a given  weight  of  steam  of  known  pressure. 

In  considering  the  introduction  of  a special  engine  for  driving  the  fan  of  a 
heating  apparatus,  it  should  be  clearly  realized  that  a certain  amount  of  steam 
being  required  for  supply  to  the  heater,  the  passage  of  that  steam  through  the 
engine  on  its  way  to  the  heater  entails  very  little  loss  in  its  heating  power,— so 
little,  in  fact,  that  the  actual  expense  of  driving  the  fan  may  be  disregarded  and 
the  steam-engine  cylinder  may  be  looked  upon  as  merely  an  enlargement  of 
the  steam  pipe.  Evidently  this  feature  of  this  system  has  its  influence  on  the 
relative  cost  of  driving  the  fan  by  engine,  or  by  electric  motor,  for,  in  the 
employment  of  the  latter  there  is  no  incidental  return  whereby  the  cost  of  power 
is  reduced. 


34 


M VENTILATION  and  HEATING« 

TABLE  No.  $. 

Of  Weight  of  Steam  in  Pounds  per  Minute  that  will 
Flow  through  Pipes  of  Given  Diameter  with 
Loss  of  One  Pound  of  Pressure. 


Initial  Gauge  DIAMETER  OF  PIPE  IN'  INCHES.  LENGTH  OF  EACH  =240  DIAMETERS. 


Pressure  in 


Lbs,  per  Sq.  In.  i 

3/ 

1 

1 y2 

2 2K 

3 

4 

5 

6 

8 

10 

1 

I . l6 

2.07 

5-7 

10.27  15.45 

25-3S 

46.85 

77-3 

1 1.5-9 

2JI-4 

341-1 

10 

i-44 

2-57 

7-1 

12.72  19  15 

31  45 

58-05 

95-8 

143-6 

262  0 

422.7 

20 

1.70 

3.02 

8-3 

14.94  22.49 

36  94 

6S.20 

112.6 

16S.7 

307-8 

496-5 

30 

1. 91 

3-4° 

9-4 

16.84  : 25-3S 

41.63 

CO 

NO 

1^ 

126.9 

:9o.i 

346.S 

559-5 

40 

2.10 

3-74 

10.3 

18.51  27. S7 

45-77 

84.49 

139-5 

209  O 

3Si-3 

615-3 

50 

2 27 

4.04 

I 1.2 

20.01  30.13 

49.48 

9'-34 

150.S 

226.0 

412.2 

665.0 

60 

M3 

4-32 

11.9 

21.38  32.19 

52.S7 

97.60 

l6l  . I 

24i-5 

440-5 

710.6 

70 

2 -57 

4-53 

12  6 

22.65 -I  34-10 

56. 00 

103  37 

170.7 

255-8 

466.5 

752-7 

80 

-•7‘ 

4.S2 

13-3 

23-82  35-87 

58.91 

108.74 

179-5 

269.0 

490.7 

79i-7 

90 

2.83 

5-°4 

!3-9 

24-92  37-52 

6l  62 

ii3-74 

CO 

G. 

CO 

281.4 

513-3 

828.1 

100 

2-95 

5-25 

H 5 

25-96  39-07 

64.18 

--t* 

CO 

195.6 

293.1 

534-6 

862  6 

120 

3->6 

5 63 

VS  5 

27-S5  4' -93 

6S  S7 

127.12 

209.9 

3H-5 

573-7 

925.6 

DETERMINATION  OF  FAN  CAPACITY.  In  the  case  of  a factory,  or 
building  of  similar  construction  and  uses,  to  be  heated  by  the  blower  system, 
the  matter  of  heating  is  usually  considered  of  most  importance,  and,  therefore, 
the  exact  average  air  change  is  first  to  be  decided  upon,  a matter  largely 
dependent  upon  sound  judgment.  As  already  stated,  this  ranges  from  fifteen 
to  twenty  minutes,  according  to  circumstances.  But  no  matter  what  the  average 
time  of  change,  certain  exposed  rooms  should  receive  a larger  volume  of  air 
than  their  proportional  cubic  contents  would  demand ; on  the  other  hand,  well- 
protected  and  interior  rooms  demand  a much  smaller  supply.  If  all  the  rooms 
are  not  to  be  heated  to  the  same  temperature,  a further  correction  is  to  be  made. 

It  is  to  be  noted,  however,  that  a stated  increase  in  the  air  supply  to  a given 
room  will  not  produce  a proportional  increase  in  its  temperature.  In  the  light  of 
the  preceding  remarks  upon  the  effect  of  ventilation  on  heating,  it  must  be 
evident  that,  the  temperature  of  the  entering  air  remaining  the  same,  if  its 
volume  be  doubled  the  loss  by  leakage  of  air  will  be  doubled  also,  while  the 


VENTILATION  and  HEATING 


normal  loss  by  conduction  and  radiation  will  remain  the  same,  so  long  as  the 
temperature  of  the  room  does  not  change.  But  naturally  the  room  temperature 
will  rise,  causing  a still  further  loss  of  heat  by  leakage,  because  of  the  higher 
temperature  of  the  increased  volume,  whereby  more  than  twice  as  many  heat 
units  escape  per  minute.  On  the  other  hand,  the  transmission  loss  will  have 
become  greater  only  in  proportion  to  the  increased  difference  between  indoor 
and  outdoor  air. 

It  is,  therefore,  evident  that  some  means  is  necessary  by  which  special 
allowance  may  be  made  in  the  air  volumes  delivered  to  those  rooms  in  which 
temperatures  are  to  be  maintained  that  differ  from  that  assumed  as  the  average 
of  the  building.  By  a process  of  reasoning,  similar  to  that  previously  employed 
in  discussing  the  effect  of  ventilation  on  heating,  a series  of  factors  may  be 
determined  which  will  aid'  in  the  ready  solution  of  heating  and  ventilating 
problems  in  which  a change  of  temperature  is  dependent  upon  a change  in  the 
air  volume  supplied. 

The  process  can  best  be  explained  algebraically,  and  then  illustrated  by  some 
practical  examples.  If  we  designate  by  x the  temperature  of  the  entering  air 
under  certain  conditions,  and  by  y the  difference  between  the  temperature  main- 
tained indoors  and  that  existing  out-of-doors,  it  is  evident,  upon  the  basis  pre- 
viously employed,  that  the  total  losses  by  leakage  and  by  transmission  would  be 
respectively  represented  thus : 

Leakage  = A-  x * =y 

Transmission  = v — — x x = x — v 

X 

If  now,  with  the  same  entering  temperature  is  should  be  desired  to  maintain  a 
difference  between  indoors  and  outdoors  different  from  y and  expressed  by  2 then 
the  loses  would  be  : 

Leakage  = — x x = z 

_ . . .r  — ar 

Transmission  - x x = x — z 


But,  whereas,  in  the  first  instance  the  transmission  loss  was  indicated  bv  x—y 
the  available  supply  for  this  purpose  is  now  represented  by  * — Whether  this 
amount  is  sufficient  will  depend  upon  the  relative  values  of  y and  and  evi- 
dently the  total  supply  in  units  necessary  to  meet  the  loss  by  transmission  under 

Z 

the  new  conditions  will  be  — (x—y)  while  the  volume  of  entering  air  at  the 


36 


a VENTILATION  and  HEATING 


(x—y) 


z (x—y) 

y (x — z) 


times 


same  temperature  as  before  will  have  to  be  — - — 

that  in  the  first  case. 

The  loss  by  leakage  will,  on  the  other  hand,  be  altered  in  the  proportion  of 
due  to  the  changed  difference  between  indoor  and  outdoor  temperature, 
further  modified  by  the  changed  volume  expressed  by  the  proportion  of 


(x—y) 


so  that  the  total  loss  will  be  represented  by 


- (x—y 


Leakage 


X 


x y 


y2  (x  -r)  _ (x—y) 


y (x—z) 


For  the  sake  of  illustration  let  us  now  take  the  case  of  a factory  in  which 
the  air  supply  at  a temperatue  at  140°  is  of  sufficient  volume  to  change  that 
within  the  building  every  16  minutes  and  to  maintain  therein  a temperature  of 
70°,  the  outdoor  temperature  being  at  0°.  Under  these  conditions  * = 140,° 
y = 70°  and 

y - - 70 


Leakage 
Transmission 


X a = ' x 140  = 70 
a-  140 


x—y 


X a = 


140—70 

140 


X 140  = 70 


If  now,  it  be  desired  to  maintain  the  building  or  any  room  within  it  at  80° 
— which  would  represent  z in  the  formula,  then 

, , z 80 

Leakage  — X a = — - X 140  = 80 

x 140 

_ . . .v— z 140—80 

Transmission  = X a = — x 140  = 60 

a 1 40 


and  the  formula 


* (x—y) 


becomes 


80  (140—70)  _ 80  ( 70)  _ 5,600 


= 1-33 


y (x—z)  70  (140—80)  70  (60  ) 4,200 

That  is,  I.33  times  as  much  air  will  be  required  to  maintain  an  internal 
temperature  of  80°  as  one  of  70°.  It  is  evident  that  this  is  a relative  value,  and 
is  not  dependent  upon  the  original  time  for  air  change,  and  may,  therefore,  be 
applied  relatively  even  if  the  time  of  change  is  not  known.  Under  the  stated 
conditions,  however,  the  air  volume  necessary  to  maintain  a temperature  of  80° 
would  be  equivalent  to  air  change  once  in  12  minutes. 


37 


VENTILATION  and  HEATING 


The  results  of  a series  of  calculations  by  this  method,  on  the  basis  of  a given 
volume  of  air  at  140°  being  capable  of  heating  the  given  building  to  various 
temperatures  from  30°  to  110°  are  represented  by  the  accompanying  curves 
(Fig.  4),  from  which  may  be  read  the  factor  to  be  employed  for  any  given  differ- 
ence in  temperature  between  indoor  and  outdoor  air,  each  curved  line  representing 
factors  for  any  basis  temperature  at  which  the  given  volume  at  140°  will  main- 
tain the  building,  the  factor  l applying  when  the  basis  temperature  as  indicated 
on  the  curve  is  to  be  maintained.  For  instance,  if  the  heating  apparatus  is  to 
be  based  upon  the  relative  size  required  to  maintain  a difference  of  temperature 
of  70°,  all  factors  will  be  read  from  the  curve  marked  70°,  and  the  factor  for  any 
other  difference,  as  80°,  will  be  obtained  by  following  up  the  vertical  line  above 
the  temperature  until  it  intersects  the  curve  of  70°  and  then  reading  the  value  at 
the  left.  Of  course,  the  factors  hold  only  for  the  specified  temperature  of  entering 
air,  but  similar  sets  of  curves  may  be  readily  developed  by  the  same  method  for 
other  temperatures.  As  the  curves  are  worked  out  for  differences  in  temperature, 
it  must  be  evident  that  to  obtain,  for  instance,  the  factor  for  a basis  temperature 
of  20°  below  zero  outside  and  70°  inside,  the  curve  for  the  total  difference,  viz., 
90°,  must  be  used. 

If  the  contents  of  the  various  rooms  of  the  building  have  been  tabulated, 
the  factors  thus  obtained  may  be  most  readily  applied  by  simply  multiplying  by 
them  respectively  the  contents  of  such  rooms  as  are  to  be  heated  to  the  tempera- 
tures to  which  they  correspond  and  then  proportioning  fan,  pipe  and  flue  area 
relatively  to  their  corrected  contents. 

Under  the  following  illustrative  conditions  of  contents  and  desired  tempera- 
tures, writh  outdoor  temperature  of  0°,  the  factors  would  be  applied  to  make  the 
apparent  relation  of  contents  as  shown  : 


Capacity  of  Room 

Desired 

Relative  Capacity  of 

in  Cubic  Feet. 

Temperature. 

Factor. 

Room  in  Cubic  Feet. 

65,000 

60° 

•75 

48,750 

30,000 

90° 

1.8 

54.000 

95,000 

40° 

.4 

38,000 

45,000 

70° 

1. 

45,000 

50,000 

50° 

•55 

27,500 

75,ooo 

80° 

1 33 

100,000 

360,000 

313.250 

Hence,  if  it  is  estimated  or  known  that  a given  air  change  will  heat  the 
entire  structure  to  70°,  it  will  require  only  ttfros  = .87  as  much  air  supply  per  unit 
of  time  to  accomplish  the  desired  results  as  above  specified.  The  vast  difference 


38 


FACTORS- 


m VENTILATION  and  HEATING  M 


FIG.  4.  Factors  for  Proportioning  Air  Supply. 


VENTILATION  and  HEATING 


between  requirements  at  high  and  low  temperatures  is  evident  in  the  factors  for 
40°  and  90°,  the  latter  being  4.5  times  the  former.  If  carried  to  its  limits  this 
method  of  calculation  will  show  no  air  change  to  be  required  at  zero  and  an 
infinite  change  to  maintain  the  same  temperature  as  that  of  the  entering  air. 

Of  course,  it  must  be  understood  that  corrections  for  exposure  and  materials 
of  construction  should  be  applied  wherever  possible,  and  that  these  factors 
are  only  to  be  employed  in  approximate  work.  The  curves  are,  however,  in- 
tended to  cover  average  conditions,  subject  to  individual  corrections  for  various 
rooms,  and  as  such  indicate  the  relative  air  volumes  required  under  equivalent 
conditions  of  exposure  and  construction. 

This,  then,  is  the  method  of  determining  the  fan  capacity  required  where  the 
calculations  are  based  merely  upon  the  times  of  air  change — the  system  generally 
adopted  for  factory  and  similar  work.  For  public  buildings  and  the  like,  where 
ventilation  is  the  vital  feature  of  the  system  and  the  number  and  activity  of  the 
occupants  can  be  definitely  determined,  the  total  air  supply  is  to  be  based  upon 
the  predetermined  provision  per  head.  The  general  allowances  for  various  classes 
of  buildings  have  already  been  given  so  that  it  is  only  necessary  to  decide  upon 
the  allowance  to  be  made  in  the  given  case  under  consideration  and  multiply  this 
by  the  total  number  of  occupants.  To  the  volume  thus  determined,  must  be 
added  the  amount  to  be  provided  for  corridors,  cloak  and  toilet  rooms,  and  for 
apartments  not  intended  for  regular  occupancy.  The  aggregate  volume  to  be 
supplied  should  obviously  be  made  sufficient  for  the  maximum  requirements  and 
the  system  so  arranged  that  proper  distribution  will  be  secured  where  the  mini- 
mum supply  is  provided. 


SELECTION  OF  FAN.  The  capacity  of  a fan  is  evidently  measured  by 
the  number  of  cubic  feet  of  air  it  can  deliver  per  unit  of  time  at  a stated  speed. 
The  efficiency  of  the  type  of  fan,  therefore,  enters  as  a determining  factor  in 
deciding  upon  its  size.  In  any  extended  system  of  heating  and  ventilation  of 
which  the  fan  forms  an  element,  it  is  necessary  that  the  peripheral  type  of  dis- 
charge be  adopted  in  order  to  overcome  the  existing  resistances  of  ducts  and 
flues.  The  disc  or  propeller  type,  which  forces  the  air  in  lines  parallel  to  its 
shaft,  is  very  inefficient  where  such  resistances  exist ; but  a fan  wheel,  either 
cased  or  open  and  delivering  the  air  at  its  periphery  in  a more  or  less  radial 
direction,  is  capable  of  meeting  all  requirements.  It  is  evident  that  the  primary 
factors  entering  to  determine  the  capacity  of  a fan  of  given  type,  are  its  size  and 
the  speed  at  which  it  is  driven.  The  volume  of  air  delivered  by  a fan  practically 
varies  directly  with  the  speed,  while  the  air  pressure  created  changes  in  propor- 


40 


VENTILATION  and  HEATING 


tion  to  the  square  of  the  number  of  revolutions,  and  the  power  required  to  drive 
the  fan  varies  in  the  ratio  of  the  cube  of  the  speed.  That  is  to  say,  doubling 
the  speed  of  a fan  doubles  the  volume  delivered  (which  is  the  measure  of  its 
capacity),  increases  the  air  pressure  created  to  four  times  that  previously  existing, 
while  the  power  required  rises  to  eight  times  that  at  half  speed. 

These  facts  should  be  clearly  borne  in  mind  in  the  selection  of  a fan,  and,  so 
far  as  circumstances  will  permit,  a large  fan  operating  at  moderate  speed  should 
be  chosen,  as  a means  of  not  only  decreasing  the  power  required  but  of  also 
reducing  the  losses  due  to  excessive  friction  in  the  ducts  incident  to  the  move- 
ment of  air  at  higher  pressure.  For  factory  and  mill  work  the  fan  may  approach 
nearer  to  the  minimum  size,  for  higher  air  velocities  are  not  only  permissible 
but  frequently  desirable  to  force  the  air  long  distances,  while  the  usual  presence 
of  an  experienced  engineer  ensures  more  frequent  attention  where  the  fan  is 
constantly  operated  at  high  speed.  In  the  schoolhouse,  the  theatre,  the  church, 
and  similar  structures,  where  a much  more  complete  system  of  air  distribution  is 
necessary  and  where  only  low  velocity  currents  are  permissible,  the  fan  should 
be  of  the  maximum  size,  capable  of  delivering  the  required  volume  of  air  at  the 
least  practicable  speed. 

To  summarize,  it  is  necessary  in  the  selection  of  a fan  to  first  determine  its 
required  capacity,  to  then  decide  upon  the  type  to  be  adopted,  and  to  finally 
select  the  size  best  adapted  to  the  given  requirements  as  largely  influenced  by  the 
maximum  speed  allowable.  Such  selection  cannot  be  alone  based  upon  published 
tables  of  fan  capacities,  for  even  with  the  type  of  fan  clearly  defined  there  is 
opportunity  for  disastrous  mistakes  in  deciding  upon  speed  and  in  making  the 
allowances  that  are  necessary  for  the  loss  in  volume  moved,  due  to  the  resistances 
encountered  in  passing  through  the  heater  and  through  the  distributing  ducts. 
The  tendency,  from  a commercial  standpoint,  is  strongly  toward  the  selection 
of  too  small  a fan  and  to  this  fact  is  due  the  failure  of  many  of  the  earlier  plants 
installed  under  the  specifications  of  those  who  possessed  but  limited  experience  in 
these  matters.  Therefore  the  selection  of  the  type  of  fan  and  the  determination 
of  its  size  should  be  left  to  parties  fully  qualified  to  decide  upon  this  important 
factor  in  the  heating  and  ventilating  system. 

GENERAL  ARRANGEMENT  OF  THE  STURTEVANT  SYSTEM.  As 
already  indicated,  the  Sturtevant  System  of  Heating  and  Ventilation  compre- 
hends only  that  method  by  which  ventilation  is  secured  under  plenum  conditions, 
that  is,  where  the  air  is  forced  into,  rather  than  exhausted  from,  the  building,  and 
comprises  in  its  entirety  a steam  heater  or  heaters,  a fan  driven  by  some  type  of 


41 


M VENTILATION  and  HEATINGM 

motor  and  a system  of  ducts  and  flues  through  which  the  air  is  forced  to  the 
various  apartments  of  the  building.  The  size  and  arrangement  of  these  ducts  and 
tines,  as  well  as  the  location  of  the  apparatus,  is  directly  dependent  upon  the  con- 
struction and  use  of  the  building. 

Although  several  States  now  legally  require  adequate  ventilation  in  factory 
buildings,  yet  it  must  be  admitted  that  in  the  introduction  of  the  Sturtevant 
System  the  owner’s  first  motive  is  usually  mercenary  rather  than  humanitarian. 
But  the  Sturtevant  System  fortunately  possesses  this  particular  feature,  con- 
sidered solely  as  a heating  system,  namely,  that  in  order  to  heat  successfully  it  is 
necessary  to  supply  a volume  of  air  sufficient  at  the  same  time  to  thoroughly 
ventilate  any  ordinary  factory  structure  where  the  processes  are  no  more  than 
ordinarily  objectionable. 

The  introduction  of  the  Sturtevant  System  is,  therefore,  divided  between  two 
great  classes  of  buildings. 

First,  where  heating  is  pre-eminent  and  ventilation  is  merely  incidental,  and— 

Second,  where  the  system  of  ventilation  is  of  primary  importance,  and  heat- 
ing is  necessarily  combined  with  it  for  successful  operation  rather  than  introduced 
as  an  independent  system. 

To  the  first  class  belong  almost  exclusively  all  manufacturing  buildings,  store- 
houses, drying-rooms,  exposition  buildings,  and  some  offices  and  stores. 

In  the  second  class  are  those  buildings  in  which  specially  objectionable  pro- 
cesses are  carried  on,  hospitals  and  asylums,  all  halls  of  audience  (including 
theatres,  churches  and  schools),  and  stores  and  offices  not  included  in  the  first  class. 

The  enterprising  manufacturer  is  quick  to  appreciate  his  financial  interest  in 
the  provision  and  maintenance  of  an  atmosphere  in  his  factory  that  exhilarates 
rather  than  wearies  his  employees ; for  a direct  monetary  return  can  be  shown  in 
the  improvement  in  quantity  and  quality  of  work  resulting  from  the  introduction 
of  this  system  with  pure  air  and  a comfortable  temperature. 

Considerations  of  economy  and  the  before-mentioned  idea  of  the  owner,  that 
heating  is  the  pre-eminent  feature  desired  in  the  application  of  the  system  in  a 
factory,  have  much  to  do  with  the  location  of  the  apparatus.  To  secure  economy 
in  heating  where  improved  ventilation  does  not  enter  into  the  question,  the  ap- 
paratus is  frequently  arranged  so  as  to  take  its  air  supply  entirely  from  within 
doors,  thereby  simply  turning  the  air  over  and  over  within  the  building.  There 
is,  however,  an  incidental  leakage  resulting  in  a degree  of  ventilation  considerably 
in  excess  of  that  occurring  with  any  system  of  direct  steam  heating.  To  this  end, 
in  a one-story  structure  the  apparatus  should  be  placed  as  near  the  centre  as  pos- 
sible, so  that  the  air  may  be  drawn  back  to  it  from  all  sides. 


42 


VENTILATION  and  HEATING 


Dependent  upon  the  character  and  construction  of  the  building,  one  of  two 
general  methods  of  distribution  may  be  adopted.  The  tirst  and  most  common  is 
by  a more  or  less  extended  system  of  metal  ducts  or  pipes,  almost  universally 
constructed  of  galvanized  iron  on  account  of  its  durability.  Such  a system  is  the 
only  one  practicable  in  wooden  structures.  In  brick  buildings,  particularly  those 
of  two  or  more  stories,  brick  ducts  and  brick  vertical  flues  are  the  most  conven- 
ient, and,  as  usually  applied,  do  not  encroach  upon  valuable  interior  floor  space. 

The  one-story  structure  with  brick,  wood  or  metal  sides,  with  sloping  roof 
surmounted  by  skylight  or  monitor,  forms  to-day  the  model  for  the  foundry  and 
the  machine,  boiler  or  blacksmith  shop,  while  its  use  is  rapidly  extending  to 
other  trades.  In  such  a building  some  arrangement  of  galvanized  iron  distribut- 
ing pipes  is  compulsory,  for  the  brick  duct  and  flue  become  too  expensive  pro- 
portionally to  the  cubic  contents  to  be  heated. 

In  comparatively  narrow  wooden  structures,  where  it  is  a question  of  galvan- 
ized iron  pipe  or  nothing,  the  main  distributing  pipe  extends  lengthwise  of  the 
basement  and  there  connects  with  risers  carried  up  alongside  of  the  supporting 
columns  of  the  building,  from  which  the  air  is  discharged  towards  the  walls 
through  properly  located  outlets  about  8 or  9 feet  above  each  floor. 

The  ideal  installation  of  the  Sturtevant  System  is  in  the  three  or  four-story 
brick  factory  of  the  type  of  the  ordinary  cotton  mill,  where  the  heated  air  is  con- 
ducted from  the  apparatus  through  a duct  in  the  basement  to  the  bases  of  special 
pilaster  flues  located  upon  the  outside  at  regular  intervals  along  one  side  of  the 
building.  The  horizontal  duct  constructed  of  brick,  usually  extends  along  the  in- 
terior of  the  basement  wall,  and  is  provided  with  either  a flat  or  arched  top  of 
approved  and  air-tight  material,  or  is  made  quadrant  in  form,  thereby  securing 
for  a given  expenditure  of  material  the  maximum  area  for  the  passage  of  air. 
At  distances  varying  from  40  to  75  feet,  the  piers  between  the  windows  are 
carried  out  and  form  the  pilaster  flues  which  receive  the  heated  air  from  the 
duct  and  discharge  it  above  the  head  line  on  each  floor. 

Most  prominent  among  the  buildings  in  which  the  ventilation  may  be  con- 
sidered of  primary  importance  are  those  in  which  persons  remain  for  several 
hours  closely  seated  and  practically  inactive,  as  is  the  case  with  an  audience  in  a 
church  or  a theatre  and  with  the  pupils  in  a schoolroom.  Here  the  per  capita  air 
space  in  the  room  is  at  its  minimum.  In  the  best  modern  schoolroom  there  is 
usually  an  allowance  of  250  cubic  feet  of  space  per  occupant ; but  in  many  theatres 
and  halls  this  figure  is  reduced  as  low  as  75  to  too  cubic  feet  to  each  person. 

In  the  ordinary  schoolroom  a supply  of  30  cubic  feet  per  head  per  minute 
would  necessitate  changing  the  entire  volume  of  the  room  once  in  about  eight 


43 


VENTILATION  and  HEATING 


minutes,  while  in  a hall  with  only  75  cubic  feet  of  space  for  each  member  of  the 
audience  such  a supply  of  air  would  require  a complete  change  once  in  every  two 
and  one  half  minutes.  It  is  difficult,  without  extreme  care,  to  so  introduce  such 
an  excessively  large  volume  of  air  under  these  latter  conditions  without  creating 
objectionable  draughts  about  the  occupants. 

In  this  climate  a perfect  system  of  heating  and  ventilation  applied  to  a build- 
ing of  the  aforementioned  class,  should, — 

First,  maintain  within  each  room  a mean  temperature  of  70°  F.,  irrespective 
of  changes  in  external  temperature,  with  a total  variation  of  not  over  2°  or  3° 
above  or  below  this  mean  at  a given  level  in  any  occupied  portion  of  the  room. 

Second,  supply  to  the  room,  under  all  conditions  of  indoor  and  outdoor 
atmosphere,  a constant  predetermined  volume  of  air,  and  deliver  it  without 
creating  objectionable  draughts  and  in  such  a manner  as  to  be  thoroughly  and 
efficiently  distributed  throughout  the  apartment. 

This  second  requirement  may  even  be  so  exacting  as  to  demand  a constant 
indoor  temperature,  with  variable  supply  of  air  proportioned  to  the  varying 
number  of  persons  occupying  the  room.  Assuredly,  with  no  arrangment  or  device 
can  the  air  supply  be  more  readily  proportioned  to  the  requirements  than  with 
the  Sturtevant  System.  Doubtless  at  the  present  time  more  attention  is  being 
given  to  improvement  in  schoolhouse  ventilation  than  to  that  of  any  other  class 
of  structures ; and  fortunately  the  ordinary  schoolhouse,  with  its  brick  partition 
walls,  presents  a most  excellent  opportunity  for  the  economical  placing  of  the 
necessary  flues,  for  they  may  be  grouped  along  the  interior  walls  and  provided 
with  inlet  openings  about  8 feet  above  the  floor  and  vent  openings  at  floor  level. 

The  hall  and  the  church  are  in  reality  but  enlarged  schoolrooms  as  regards 
their  treatment  by  the  blower  system.  The  same  vital  requirement  holds : that 
the  temperature  must  be  maintained  independent  of  volume  of  air  admitted, 
while  the  difficulty  of  satisfactorily  admitting  the  required  air  supply  is  increased 
by  the  closer  seating  of  the  audience. 

The  theatre  presents  far  more  complication  than  the  hall ; its  three  parts  — 
stage,  auditorium  and  lobbies  — may  at  one  moment  be  essentially  one  and  the 
next  be  rendered  practically  independent.  The  auditorium  is  usually  thoroughly 
protected  by  the  lobbies  or  the  walls  of  adjacent  buildings,  so  that  the  heat  loss  is 
reduced  to  a minimum,  and  during  a performance  it  becomes  a question  of  cooling 
rather  than  of  warming  the  occupants. 

In  some  cases  the  air  has  been  supplied  entirely  through  perforated  ceilings, 
whence  it  passes  down  over  the  persons  of  the  audience  and  escapes  through  a 
multitude  of  openings  in  floor  and  risers.  This  unnatural  movement  of  the  air 


44 


VENTILATION  and  HEATING 


against  its  own  impulse  must  be  facilitated  by  exhaust  fans  connected  to  the  area 
beneath  the  floor  in  addition  to  the  plenum  fans  for  forcing  in  the  fresh  air. 

The  rapid  improvement  in  theatre  ventilation  certainly  indicates  that  the 
enterprising  manager  sees  therein  another  inducement  to  the  theatre-going  public 
to  patronize  his  individual  house  in  preference  to  one  where  the  air  is  foul  and 
oppressive,  although  the  dramatic  attraction  may  be  equally  good. 

The  requirement  ot  large  air  volume  per  capita  in  hospitals  and  asylums, 
particularly  in  contagious  wards,  necessitates  positive  and  ample  means  which  can 
only  be  satisfactorily  met  by  the  fan,  standing  as  it  does,  capable,  according  to 
its  size,  of  supplying  any  amount  of  air  required.  The  store  with  its  extended 
floor  areas,  and  the  office  building  with  its  multiplicity  of  small  rooms,  call  for 
arrangements  peculiarly  their  own.  In  fact,  the  ready  adaptability  of  the 
Sturtevant  System  to  diverse  conditions  forms  one  of  its  salient  features. 
Many  illustrations  of  its  application  are  presented  in  succeeding  pages;  the 
preceding  brief  outline  being  here  given  only  to  indicate  the  general  scheme 
of  application. 


DOUBLE  DUCT  SYSTEM.  The  varying  exposures  of  the  rooms  of  a 
school  or  other  building  similarly  occupied,  require  that  more  heat  shall  be 
supplied  to  some  than  to  others.  The  sunlit,  southerly  room,  perhaps  still  more 
favored  by  being  over  the  boiler,  may  be  kept  perfectly  comfortable  with  a 
supply  of  heat  that  perchance  will  barely  maintain  a temperature  of  50°  to  60°  F. 
in  a room  on  the  opposite  side  of  the  building,  exposed  to  high  winds  and  shut 
off  from  the  warmth  of  the  sunshine.  With  a constant  and  equal  volume  of  air 
supply  to  each  room,  it  is  evident  that  its  temperature  must  be  directly  proportional 
to  the  cooling  influences  within  and  around  the  room,  and  that  no  building  of 
this  character  is  properly  heated  and  ventilated  where  the  temperature  cannot  be 
varied  without  affecting  the  air  supply. 

To  this  end,  air  of  a given  temperature  may  be  conducted  to  the  base  of  each 
flue  and  there  tempered  to  a degree  suitable  to  the  requirements  of  the  room 
supplied.  Two  methods  appear : 

The  older  arrangement  consists  in  heating  the  air  by  means  of  a primary  coil,  at 
or  near  the  fan,  to  about  60°  F.,  or  to  the  minimum  temperature  required  within  the 
building.  From  the  coil  it  passes  to  the  bases  of  the  various  flues,  and  is  there 
still  further  heated  by  secondary  or  supplementary  heaters,  one  or  more  to  each 
room.  Under  certain  conditions  the  distribution  ducts  may  be  omitted,  and  the 
entire  sub-basement  made  to  serve  as  a large  plenum  chamber  containing  air 
under  slight  pressure  heated  to  about  60°  F.  by  the  main  coil. 


45 


VENTILATION  and  HEATING 


With  the  second  and  more  recent  method  a single  heater  is  employed,  the 
supplementaries  are  discarded,  and  all  of  the  air  is  heated  to  the  maximum 
required  to  maintain  the  desired  temperature  in  the  most  exposed  rooms,  while 
variety  in  temperature  of  air  supplied  to  the  other  rooms  is  secured  by  mixing 
with  the  hot  air  a sufficient  volume  of  cold  air  at  the  bases  of  the  respective  flues. 
This  result  may  be  best  accomplished  by  designing  a hot  blast  apparatus  so 
that  the  air  shall  be  forced  rather  than  drawn  through  the  heater,  and  by  providing 
a by-pass  through  which  it  may  be  discharged  without  passing  across  the  heated 
pipes. 

This  discharge  for  the  unheated  air  is  usually  made  above  and  separate  from 
the  heater  pipes.  Extending  from  the  apparatus  is  a double  system  of  ducts,  almost 
universally  constructed  of  galvanized  iron  and  suspended  from  the  ceiling.  At 
the  base  of  each  flue  is  placed  a mixing  damper  which  is  controlled  by  chain  from 
the  room  above,  and  so  designed  as  to  admit  either  a full  volume  of  hot  air,  a 
full  volume  of  cold  air,  or  to  mix  them  in  any  desired  proportion  without  affecting 
the  resulting  total  volume  delivered  to  the  room.  Where  perfect  and  continuous 
regulation,  independent  of  the  teacher,  is  desired,  the  damper  should  be  operated 
by  a thermostat  in  the  room  with  which  the  flue  connects. 

The  hot  and  cold  system,  as  this  double  duct  is  familarly  known,  accom- 
plishes at  less  expense,  with  greater  rapidity  and  equal  certainty,  the  results  obtained 
by  the  more  complicated  method  previously  described,  and  is  being  extensively 
introduced  in  the  modern  schoolhouse  wherever  the  blower  system  is  applied.  As 
ordinarily  installed,  the  hot  air  and  the  cold  air  connection  to  each  mixing  damper 
are  of  equal  area  so  that  whether  the  air  be  hot  or  cold  or  a mixture  of  the  two, 
its  volume  will  remain  constant. 

An  accurate  calculation  of  the  resulting  temperature  when  two  known 
volumes  of  air  of  given  temperatures  are  mixed  must  take  into  consideration 
the  temperature,  weight  and  humidity  of  these  volumes;  but  for  rough  estimating 
and  for  purposes  of  comparison  the  difference  in  weights  and  humidity  may  be 
disregarded.  It  then  becomes  merely  a question  of  averaging  of  the  simplest 
kind.  Thus,  for  instance,  if  of  a stated  resulting  volume,  4 parts  were  introduced 
at  a temperature  of  30°  and  6 parts  at  a temperature  of  120°,  the  calculation 

would  be  merely  (4  X 30)  + (6  X ,120)  = ^ 

In  this  manner  the  accompanying  diagram  (Fig.  5)  has  been  laid  out  simply 
to  illustrate  the  relative  mixtures  and  resulting  temperatures  under  a given  set  of 
conditions.  As  a fair  average  for  schoolhouse  work,  120°  has  been  taken  as  the 
initial  temperature  of  the  hot  air  in  its  relation  to  various  proportional  mixtures 


46 


Initial  Temperature  of  Cold  Air  and  Resulting  Temperature  of  the  Mixture  of  HotandColdAir 


VENTILATION  and  HEATING 


Parts  of  Cold  air  in  Mixture 

01  2 3456769  io 

Parts  of  Hot  Air  in  Mixture 

FIG.  5.  Resulting  Temperatures  of  Various  Mixtures 
of  FIot  and  Cold  Air. 


47 


VENTILATION  and  HEATING 


with  cold  air  at  30°  up  to  120°  ; of  course  the  terms  “ hot  ” and  “ cold  ” become 
here  distinctly  relative ; in  fact,  they  always  are. 

The  vertical  lines  upon  the  diagram  represent  the  relative  proportions  of  hot 
and  cold  air  as  indicated  by  the  tigures  at  the  bottom,  while  the  horizontal  lines 
serve  as  measures  both  of  the  initial  temperature  of  the  cold  air  and  of  the 
resulting  temperature  of  the  mixture,  which  latter  may  be  read  from  the  diagonal 
line  ending  in  the  given  initial  temperature  of  the  cold  air.  For  instance,  the 
temperature  of  a mixture  of  3 parts  of  cold  air  of  20°  temperature  and  7 parts  of 
hot  air  of  120°  (the  basis  for  the  diagram),  may  be  read  at  the  intersection  of 
the  diagonal  from  point  20  on  the  left  and  the  vertical  from  the  point  30  and  7 
below. 

As  previously  stated,  the  correction  for  change  in  weight  due  to  change  in 
temperature  has  not  been  applied,  but  the  diagram  shows,  nevertheless,  the  results 
of  the  given  conditions  in  a manner  sufficiently  accurate  to  facilitate  ready 
comparison.  Of  course  the  cold  air  tigures  refer  to  the  temperature  of  the  air  as  it 
passes  through  the  mixing  damper.  What  its  temperature  might  have  been 
before  entering  the  apparatus  must  depend  largely  upon  the  arrangement  of  the 
system  and  the  total  amount  of  colli  air  passing  through  the  apparatus  at  the  time. 

DISTRIBUTION  OF  AIR.  Thorough  distribution  of  the  air  supplied  by 
any  system  of  ventilation  is  necessary,  not  only  for  the  best  results  in  the 
matter  of  dilution,  but  also  to  absolutely  prevent  the  possibility  of  objectionable 
draughts.  In  halls  of  audience,  where  the  occupants  are  at  rest,  any  slight 
inequality  in  the  distribution  is  particularly  noticeable ; while  in  the  workshop, 
where  all  are  in  motion  and  not  in  close  contact  with  each  other,  less  refined 
arrangements  will  give  satisfaction. 

Experiment  has  shown  that  a velocity  of  air  less  than  nineteen  inches  per 
second  is  not  perceptible  to  the  senses,  and  that  an  air  movement  as  high  as  three 
feet  per  second  is  not  objectionable.  Perception  of  draughts  depends  largely, 
however,  on  the  temperature  and  humidity  of  the  air  in  motion  as  compared 
with  that  normal  in  the  room.  It  is  evident,  therefore,  that  special  care 
should  always  be  exercised,  in  order  that  no  current  having  a velocity  in  excess 
of  three  feet  per  second,  or  one  hundred  and  eighty  feet  per  minute,  be  allowed 
to  come  in  contact  with  the  body. 

The  same  method  of  distribution  is  not  applicable  in  all  cases.  On  general 
principles,  it  may  be  asserted  that,  wherever  the  air  is  cooled  in  its  progress  or 
passage  through  a room,  that  it  will  best  serve  its  purpose  as  a means  of  heating 
and  ventilating  if  it  be  admitted  to  the  room  at  a point  mod  distant  from  the 


48 


M VENTILATION  and  HEATING« 

outer  walls.  This  point  of  discharge  should  be  at  least  eight  feet  above  the 
floor,  and  the  air  movement  should  be  directly  toward  the  outside  walls.  Such 
an  arrangement  is  very  easy  of  introduction  in  a building  having  interior  parti- 
tion walls,  as  an  office,  a dwelling,  or  a school  building,  for  the  flue  may  be 
constructed  within  or  against  these  walls.  Thus  located,  the  air  discharged  from 
the  outlet  passes  in  a constantly  spreading  volume  above  head  level  toward  the 
exposed  walls,  where,  becoming  slightly  cooled,  it  slowly  settles  to  the  floor.  To 
complete  the  circuit  and  fulfil  the  design,  the  ventilating  register  should  be  in  the 
same  inner  wall  as  the  supply  opening,  but  close  to  the  floor.  There  is  thus 
induced  toward  this  outlet  a return  flow  of  the  air  in  a well-distributed  mass. 
The  currents  are,  in  reality,  stratified,  the  lower  one  serving  to  take  up  the 
emanations  from  the  lungs  of  the  occupants  as  its  sweeps  slowly  across  them 
directly  towards  the  ventilating  register.  In  factory  heating  no  ventilating  flues 
are  provided,  as  there  is  always  sufficient  leakage  of  air  around  windows  and 
through  porous  walls ; but  the  air  should,  nevertheless,  be  introduced  above 
head  level. 

In  the  case  of  theatres,  and  of  most  halls  and  churches,  the  large  number 
of  occupants  serves,  by  the  animal  heat  generated,  to  visibly  increase  the  tempera- 
ture of  the  air  admitted.  The  conditions  are,  therefore,  exactly  the  reverse 
of  those  where  the  air  is  cooled  in  transit,  and  the  best  results  are  obtained 
by  causing  the  air  movement  to  be  directly  upward,  or,  as  in  the  case  of 
some  recent  installations,  directly  downward,  with  the  air  supply  through  the 
ceiling.  Minute  sub-division  of  the  supply  is  an  absolute  necessity  when  it  is 
admitted  through  the  floor,  and  with  either  the  upward  or  the  downward  method 
the  design  is  to  secure  individual  ventilation,  so  far  as  may  be  practically 
possible.  The  details  of  construction  necessary  to  secure  the  proper  air  move- 
ment for  these  various  classes  of  buildings  will  be  made  evident  in  the  illustra- 
tions which  follow. 

ARRANGEMENT  AND  CONSTRUCTION  OF  DUCTS  AND  FLUES. 
The  arrangement  of  the  system  of  ducts  and  flues  within  a building  must,  of 
necessity,  be  dependent  upon  the  method  of  distribution  adopted,  which  in  turn 
will  be  largely  influenced  by  the  construction  of  the  building.  If  of  brick,  the 
flues  may  be  most  readily  and  economically  built  in  the  walls  as  the  building  is 
erected.  Such  a procedure,  however,  presupposes  the  selection  of  the  system 
before  the  building  plans  are  completed.  As  natural  and  necessary  as  this  may 
seem,  it  is  lamentably  true  that  such  decision  is  very  frequently  delayed  until 
the  budding  is  under  way. 


49 


VENTILATION  and  HEATING  « 


Under  such  circumstances,  it  is  usually  necessary  to  provide  for  the  distribu- 
tion through  metal  ducts,  whose  position  is  seldom  what  it  should  be,  owing  to 
the  exigencies  of  architectural  features.  In  fact,  the  day  has  not  yet  arrived 
when  hygienic  demands  always  take  precedence  over  architectural  symmetry  and 
beauty.  Not  that  harmonious  architectural  composition  cannot  be  preserved 
when  proper  provision  is  made  for  heating  and  ventilating  flues,  but  that  the 
work  of  the  architect  is  too  frequently  schemed  and  the  drawings  completed 
without  adequate  consideration  of  the  ventilating  system  to  be  adopted.  It 
is  surprising  how  successfully  flues  can  be  introduced  without  marring  the 
general  effect,  for  it  is  a simple  matter  to  work  them  in  as  false  columns, 
pilasters,  beams,  or  cornices,  or  to  introduce  perforated  ceilings,  without  attract- 
ing attention. 

In  an  old  building  metal  ducts  and  hues  are  almost  a necessity,  the  material 
employed  generally  being  galvanized  iron.  When  ducts  are  to  be  placed  under- 
ground, they  should  be  of'  brick  for  the  larger  sizes,  while  glazed  tile  pipe  will 
serve  for  smaller  ones.  Flues — which  in  matters  of  ventilation  are  generally 
classed  as  vertical  air  passages  in  distinction  from  ducts,  by  which  name  are 
designated  the  horizontal  conduits  — should  always  be  smoothly  finished  inside, 
and  where  the  expense  will  permit,  it  is  wise  to  line  their  interiors  with  sheet 
metal,  either  tin  or  galvanized  iron,  or  with  special  terra-cotta  flue  linings  which 
are  made  for  the  purpose. 

So  far  as  possible  the  flues  should  be  banked  together  for  economy  in  con- 
struction, but  independent  flues  should  be  provided  for  individual  rooms,  to 
insure  equality  of  distribution,  except  where  they  are  large,  as  in  the  mill  and 
factory.  With  this  arrangement  a heating  flue  for  the  first  floor  may  readily  be 
stopped  off  above  the  outlet  opening  and  employed  as  a ventilating  flue  from 
the  floor  above.  It  is  best  to  carry  all  ventilating  flues  separately,  above  the 
roof,  although  very  good  results  may  be  obtained  under  the  plenum  system, 
where  they  simply  discharge  into  the  attic,  from  which  escape  is  provided 
through  a cupola  or  louvered  windows.  If  the  complicated  nature  of  the 
building  demands  that  an  exhaust  fan  be  used,  it  should  be  directly  connected 
with  the  flues.  An  exhaust  fan  simply  drawing  from  the  attic  space  and  dis- 
charging out  of  doors  will  prove  very  inefficient,  owing  to  the  ease  with  which 
a portion  of  its  supply  will  find  its  way,  by  leakage,  through  the  roof  rather 
than  be  drawn  from  the  rooms  below.  As  a result,  the  fan  performs  only  a part 
of  the  definite  duty  assigned  to  it,  and  the  amount  of  air  which  should  be 
withdrawn  from  the  rooms  is  so  seriously  reduced  as  to  decidedly  impair  the 
ventilation. 


50 


drawings  for 


Too  much  care  cannot  be  taken  in  the  design  and  construction  of  a system 
of  ducts  and  tines.  Owing  to  the  small  scale  upon  which  the  general  scheme  is, 
in  most  cases,  necessarily  shown,  and  the  general  lack  of  detail 
individual  features,  the  galvanized  iron  worker  and  the 
mason  are  usually  left,  to  a considerable  extent,  to  their 
own  devices  to  accomplish  the  desired  results.  This 
may  be  well  enough  in  the  case  of  men  experienced 
in  this  line  of  work,  as  is  particularly  the  case  with 
those  employed  continuously  on  galvanized  iron 
work  by  large  and  established  heating  and  venti- 
lating concerns.  But  the  local  tinsmith  and  the 
ordinary  mason  are  very  apt,  from  inexperience, 
to  fail  to  properly  construct  such  work. 

The  disastrous  effect  of  sudden  turns  must 
be  thoroughly  realized,  and  wherever  a change  in 
direction  is  necessary,  it  must  be  made  with  as 

generous  a curve  as  possible.  In  galvanized  iron  piping,  “ stove-pipe  elbows,” 
so-called,  should  always  be  avoided,  and  turns  of  direction  of  90°  constructed, 


ask;*  Fig.  6. 


in  the  case  of  round  pipe, 
radius  of  curvature  of  the 
to  the  diameter  of  the  pipe. 
This  proportion  of  radius 
round  or  rectangular. 

A great  source 
sistance  often  re- 
pipe squarely  into 
the  branch  nipple 
attached  to  the  pipe 
of  the  change  in 
all  as  clearly  shown 
the  main  pipe  is 
is  taken  out,  and 
very  gradual.  It  is 
piping  to  make  this 


Fig.  7. 


with  at  least  five  pieces,  and  with  the 
inner  side  of  the  elbow  at  least  equal 
Such  an  elbow  is  represented  in  Fig.  6. 
to  size  holds  whether  the  pipe  be 

of  unnecessary  friction  and  undue  re- 
sults from  the  butting  of  a branch 
the  side  of  the  main  pipe.  Instead, 
should  be  cut  into  and  securely 
at  an  angle  of  45°,  and  the  remainder 
direction  made  by  using  a half  elbow, 
in  Fig.  7.  It  is  to  be  noted  that 
reduced  in  area  after  the  branch 
that  this  reduction,  or  taper,  is 
the  usual  practice  in  well  made 
taper  equal  in  width  to  a sheet 


of  galvanized  iron,  which,  with  the  usual  thirty-inch-wide  sheet,  will  give  a net 
length  of  twenty-eight  inches  when  the  pipe  is  put  up.  The  same  method 
should  be  employed  with  regard  to  reductions  in  the  size  of  all  forms  of 
rectangular  ducts. 


VENTILATION  and  HEATING 


Wherever  a branching  or  division  of  the  main  pipe  is  to  be  made,  and  even 
in  cases  where  a relatively  large  branch  is  to  be  taken  from  the  side  of  the  main 
pipe,  the  piece  should  be  so  constructed  as  to  proportionally 

divide  the  air  currents;  that  is,  in  such  a way  that  the 

air  volume  X \ is  practically  split  by  the  opposing  acute 

angle , and  easily,  but  positively , compelled  to  change 

its  direction  iW  movement.  Such  a branch,  or  divided 

outlet,  is  il-  AT'|;  f/  lustrated  in  Fig.  8,  as  applied  to  a round 

pipe.  Rect-  jr  jj  angular  pipe  should  be  treated  upon  the 

same  gen-  ‘ - era'  principle,  which  is  here  much  more 

easily  ap-  ~ ^ plied.  Fig.  9 indicates  the  form  in  which 

it  should  be  constructed  where  one  portion  is  to  con- 
tinue in  the  same  direction  and  the  other  turn  to  a 

direction  at  ^ O x right  angles.  In  reality,  the  reduction 

in  area  be-  ^ig.  yond  the  branch  is  made  in  the  process 

of  taking  out  the  branch,  and  by  its  arrangement  serves  to  catch  and  deflect 
the  requisite  amount  of  air.  Pipe  of  this  form  and  construction  is  largely 
employed  in  public  building  and  schoolhouse  work,  for  the  purpose  of  distribut- 
ing the  heated  air  from  the  apparatus  to  the  bases  of  the  various  vertical  flues. 
When  thus  employed,  it  is  usually  suspended  close  beneath  the  basement  ceiling, 
and  made  of  such  depth  as  to  allow  ample  head 
room,  thus  forming  as  a rule  a com- 
paratively flat  pipe. 

With  all  due  regard  in  the  design 
to  the  unequal  resistances  of  ducts  and 
flues  of  different  areas  and  lengths,  it  is 
always  best  to  additionally  provide,  in 
the  main  supply  system,  the  means  of 
primary  permanent  equalization  of  air 
volumes  to  the  various  flues.  To  this  end, 
all  such  branches  as  that  shown  in  Fig.  9 
should  be  provided  with  light  and  short  flap 
dampers,  easily  adjusted  from  outside  the  pipes  Fig.  9. 
and  permanently  held  in  place  by  set-screwing  the  rods  when  turned  to  the  proper 
position.  This  damper  is  very  clearly  indicated  in  the  cut.  In  small  pipes,  a 
mere  extension  of  flexible  sheet  iron  from  the  dividing  angle  will  serve  the 
purpose,  and  may  be  adjusted  through  a handhole  in  the  pipe,  which  should  be 
provided  with  a slide. 


52 


VENTILATION  and  HEATING 


The  same  principles  hold  in  the  construction  of  brick  ducts  and  the  intro- 
duction of  tile  pipes.  The  difficulty  in  brickwork  generally  lies  in  the  un- 
willingness of  the  mason  to  introduce  curves,  because  of  the  extra  care  required 
in  laying'  them.  But  misproportioned  brick  ducts,  and  the  lack  of  proper 
adherence  to  drawings,  has  resulted  in  serious  trouble  in  many  cases.  A typical 
construction  is  presented  in  Fig.  10,  and  it  is  to  be  noted  how  easily  the  air  is 
deflected  into  the  side  branch.  The  tops  of  such  ducts  may  be  arched,  as 
shown,  or  may  be  covered  with  properly  spaced  T irons,  between  which  bricks 
are  laid  and  thoroughly  bedded  in  mortar. 


is  obviously  determined  by  the  volume  of  air  destined  to  pass  through  it  and 
the  permissible  or  desirable  rate  of  flow.  From  a consideration  of  the  fact  that 
the  losses  due  to  friction  of  air  in  its  movement  through  pipes  increase  as  the 
square  of  the  velocity,  so  that  doubling  the  velocity  increases  the  friction  four- 
fold, it  would  at  first  appear  that  the  ultimate  object  in  any  design  should  be  to 
move  the  air  at  the  lowest  possible  velocity,  but  the  accomplishment  of  such  an 
object  obviously  demands  ducts  of  vast  size.  It  is  plainly  evident,  however, 


53 


VENTILATION  and  HEATING 


that  the  interest  account  on  the  increased  cost  of  such  ducts  may  readily  exceed 
the  saving-  in  power  attained  by  reducing  the  rate  of  air  movement.  It  is  further 
true  that,  in  any  successful  system  of  ventilation,  it  is  necessary,  in  order  to 
secure  positive  circulation,  that  the  velocity  and  pressure  of  the  air  should  not 
be  allowed  to  fall  below  a prescribed  minimum.  But,  most  important,  as  render- 
ing the  general  question  of  velocities  of  still  less  importance  from  an  economical 


TABLE  No.  6. 

Of  the  Losses  in  Pressure  and  Horse  Power  Due  to 
Priction  of  Air  Passing  Through  Pipes. 


Diameter 

Loss  OF 

VELOCITY  OF  AIK  IN'  FEET  PER  MINUTE. 

Pressure 

of  Pipe 

and 

in  Inches. 

Horse  Power. 

lOOO 

1200 

1400 

1600 

1800 

2000 

2200 

2400 

2600 

12 

( I/Os?* of  Pressure 
J iuozs.  persq.  in. 

.092 

•‘33 

. 1 S i 

•237 

■3°° 

■370 

.44S 

•533 

.626 

j Ilorse  Power 
lost  in  Friction. 

.0198 

•0343 

■0544 

.0S12 

• 1156 

.1586 

.2111 

.2741 

■34S5 

18 

( Lass  of  Pressure 
J inoza.peraq.  in. 

.062 

.0S9 

.121 

.158 

.200 

•247 

.299 

•356 

-4*7 

j Horsepower 
( lost  in  Friction. 

.0297 

.0^12 

.0816 

.121S 

•‘735 

.2380 

■3*67 

.41  12 

•522S 

24 

( I .oss  of  Pressure 
J inoza.peraq.  in. 

.046 

.067 

.091 

.119 

.150 

.185 

.224 

.267 

•3  >3 

i Horse  Power 
| lost  in  Friction. 

•°397 

.0685 

.1088 

.1624 

•23 ‘3 

• 3 1 7 3 

•4223 

CO 

CO 

T 

ir 

.6971 

30 

C Lass  of  Pressure 
J inozs.peraq. in. 

•037 

•053 

•073 

•095 

.120 

.148 

..79 

.213 

.250 

j Horse  Power 
( lost  in  Friction. 

.0496 

.0837 

.1360 

.2031 

.2S91 

3966 

•5279 

.6855 

.8714 

36 

( Lass  of  Pressure 

1 in  ozs.  persq.  in. 

.031 

.044 

.060 

.079 

.100 

.123 

•‘49 

.178 

.209 

1 Horse  Power 
( lost  in  Friction. 

•0595 

. IO24 

.1632 

•2437 

•3469 

•4759 

•6334 

.S224 

1.0456 

44 

( Lass  of  Pressure 

.025 

.036 

.049 

.069 

.082 

.IOI 

.122 

•‘45 

.171 

j Horse  Power 
( lost  in  Friction. 

.0727 

• 1 256 

•1995 

.2938 

.4240 

•58*7 

•7742 

I .005  I 

1.2779 

52 

( Loss  of  Pressure 
' /-  per aq.  in. 

.021 

.031 

.042 

•055 

.069 

.085 

.‘03 

•‘23 

.144 

i Horse  Power 
( lost  in  Friction. 

•0S59 

.14S5 

.2360 

•3520 

.5011 

.6874 

.9150 

1.1S79 

‘•5‘03 

( Lass  of  Pressure 

.036 

.060 

60 

J in  ozs.  per  aq.  in. 

.019 

.027 

.047 

.074 

.090 

.107 

.125 

j Horae  Power 
( lost  in  Friction. 

.0991 

- 1 7 1 3 

.2721 

.4061 

•5782 

•7932 

1.1607 

1.3706 

1 7427 

standpoint,  is  the  fact  of  the  almost  universal  employment  of  the  steam  engine 
for  driving  the  fan  in  connection  with  the  Blower  System.  The  common  prac- 
tice of  utilizing  the  exhaust  steam  in  the  heater  reduces  the  actual  cost  of  moving 
the  air  to  practically  nothing.  Table  No.  6 presents,  in  limited  form,  the  rela- 


54 


VENTILATION  and  HEATING« 

tion  existing  between  size  of  pipe,  velocity  of  air,  and  losses  'in  pressure  and 
horse-power.  These  losses  are  proportional  to  the  area  of  the  pipe  surface  with 
which  the  air  comes  in  contact ; therefore,  a round  pipe  offers  the  least  resistance 
per  cubic  foot  of  air  moved,  a flat  rectangular  pipe  being  most  inefficient. 

In  almost  all  public  building  work,  the  definite  object  of  the  system  is  to 
deliver  the  air  to  the  rooms  at  such  velocity  as  to  secure  its  movement  to  the 
desired  points,  but  without  objectionable  draughts,  or  the  humming  of  the  air  as 
it  passes  through  the  registers,  which  latter  is  very  likely  to  occur  at  velocities  of 
about  1,000  feet  per  minute.  To  this  end,  the  average  velocity  through  the  net 
area  of  the  screen  or  register  should  not,  under  ordinary  conditions,  exceed  500 
feet  per  minute.  For  average-sized  schoolrooms  a velocity  as  low  as  400  feet  is 
more  desirable,  while  in  small  rooms,  as  in  dwellings,  this  may  well  be  reduced 
to  300  feet  per  minute.  It  is  always  best  to  keep  the  velocity  through  floor 
registers,  at  least,  as  low  as  this,  and  preferably  lower  still.  To  secure  a fairly 
equable  discharge  through  the  full  area  of  a screen  or  register  supplied  from  a 
vertical  flue,  the  velocity  in  this  flue  should  not  exceed  that  through  the  outlet 
by  more  than  fifty  per  cent.  Ordinarily,  flue  velocities  in  such  buildings  range 
from  500  to  800  feet  per  minute.  The  rate  of  flow  through  the  connections  to 
the  bases  of  the  flues  should  in  turn  be  higher  than  that  through  the  flues  them- 
selves, while  the  velocity  in  the  main  horizontal  distributing  ducts  would  be  even 
higher.  In  fact,  in  buildings  of  this  class  the  plan  should  be  to  gradually  reduce 
velocities  from  the  point  of  leaving  the  fan  to  the  point  of  discharge  to  the 
rooms.  Careful  investigation  has  shown  that,  everything  considered,  the  velocity 
in  the  main  horizontal  ducts  from  the  fan  should  not  be  below  1,500  feet,  and 
preferably  2,000  feet,  per  minute. 

In  the  case  of  a manufactory,  or  wherever  rooms  are  of  excessive  size,  the 
treatment  should  be  radically  different.  Here,  a high  velocity  is  necessary  to 
assure  the  passage  of  the  air  to  the  most  distant  points.  It  is  not  at  all  infrequent 
in  such  buildings  to  force  it  100  to  200  feet  from  the  outlet.  The  conditions 
which  will  permit  of  such  air  movement  will  be  made  more  evident  in  succeed- 
ing illustrations  of  the  system  as  applied  to  manufacturing  establishments. 
A high  velocity  at  the  discharge  outlet  is  evidently  necessary  to  force  the  air  for 
such  a distance  through  the  open  room.  Very  slight  increase  is,  therefore,  made 
over  the  area  of  the  fan  outlet.  As  the  fan  in  such  a building  is  usually 
operated  at  its  maximum  speed, — the  air  leaving  its  outlet  at  a velocity  of  about 
3,500  feet  per  minute, — even  a fairly  generous  increase  in  areas  will  maintain 
its  discharge  through  the  flue  outlets  at  velocities  of  from  2,000  to  3,000  feet  per 
minute.  Of  course,  with  such  high  velocities,  the  frictional  losses  are  increased ; 


55 


VENTILATION  and  HEATING  M 


but,  the  fan  being  operated  at  higher  speed,  the  proportional  losses  are  no 
excessive,  while  the  rapidity  of  movement  reduces  the  time  during  which  the 
moving  air  within  the  conduits  may  part  with  its  heat  to  the  surrounding 
atmosphere. 

According  to  the  character  of  the  building,  two  methods  appear  for  figuring 
the  ducts  and  flues.  In  a manufactory  — after  determining  the  fan  capacity 
required  and  the  relative  volumes  of  air  necessary  for  the  various  rooms,  as  based 
upon  their  cubic  contents,  their  desired  temperature  and  their  exposure — there 
may  be  calculated  a constant  number  representing  the  square  inches  of  outlet 
of  the  fan  per  l ,000  cubic  feet  of  space  as  reduced  to  a standard  of  heating  to 
the  basis  temperature.  In  a compact  system,  with  a small  number  of  outlets, 
ic  is  a very  common  custom  to  make  the  aggregate  area  of  these  outlets  about 
twenty-live  per  cent,  in  excess  of  the  area  of  the  fan  outlet.  From  this  may  be 
determined  the  square  inches  of  pipe  outlet  per  1,000  cubic  feet  of  space,  and 
the  areas  proportioned  to  the  requirements.  This  excess  of  area  of  outlets  over 
the  fan  outlet  demands  that  the  main  pipe  shall  not  be  reduced  exactly  in 
proportion  to  the  outlets  taken  from  it  as  it  extends  from  the  fan,  but  at  such  a 
less  ratio  that  at  the  end  of  the  system  the  main  pipe  shall  be  practically  equal 
to  the  area  of  the  last  outlet  or  group  of  outlets. 

In  a school  or  similar  building,  where  the  hot  and  cold  duct  system  is  to  be 
introduced,  and  the  air  distribution  is  to  be  made  respectively  proportional  to  the 
number  of  occupants  of  the  individual  rooms,  the  process  is  practically  the 
reverse.  The  register  or  screen  area,  dependent  upon  the  selected  velocity 
through  the  same,  will  be  determined  by  dividing  the  total  volume  per  minute 
by  the  rate  of  flow  per  minute.  The  flue  area  will,  in  turn,  be  determined 
in  a similar  manner,  and  thus  the  distributing  system  will  be  worked  out  back- 
ward, so  to  speak,  through  lines  of  increasing  velocities,  to  the  fan  itself.  It  is 
very  desirable,  however,  to  maintain  through  the  connection  at  the  base  of  each 
flue  a velocity  considerably  higher  than  that  in  the  flue,  in  order  to  counteract 
all  tendency  to  unequal  flow,  and  to  render  any  adjustment  of  the  primary  dis- 
tributing dampers  more  efficient. 

To  facilitate  calculation  by  either  method  of  figuringthe  distributing  system, 
Tables  Nos.  7 and  8 have  been  prepared,  the  one  showing  the  area  in  square 
inches  of  flue  or  register  required  for  any  given  air  change,  and  the  other  the 
flue  or  register  area  necessary  for  the  passage  of  any  given  volume  at  a stated 
velocity.  Values  for  volumes  below  100  or  above  1,000  cubic  feet  may  be 
readily  determined  from  the  latter  table  by  reading  for  the  multiple  of  the  given 
volume,  and  then  pointing  off  the  requisite  number  of  places.  Thus,  if  a 


56 


TABLE  No.  7. 

Number  of  Square  Inches  of  Flue  Area  Required  per 
1,000  Cubic  Feet  of  Contents  for  Given 
Velocity  and  Air  Change. 


VELOCITY  OF  AIR  IX  FLUE  IX  FEET  PER  MIXUTE. 


No.  Minutes  to 


Change  Air, 

300 

400 

500 

600 

700 

800 

900 

IOOO 

noo 

1200 

1300 

1400 

1500 

4 

120. 

90. 

7 2 ■ 

60. 

51.6 

45- 

40. 

36. 

32-2 

3°- 

27.6 

25.6 

21  4 

5 

96. 

72.2 

57-6 

4S. 

41. 1 

36.1 

32  • 

2S.S 

26.2 

24- 

22.2 

20.5 

19.2 

6 

So. 

60. 

4S. 

40. 

34-3 

30- 

26.6 

24. 

21. S 

20. 

18. s 

17. 1 

l6. 

7 

6S.6 

5 1 -4 

41. 1 

34-3 

29.4 

2 5-7 

22.9 

20.6 

1S.7 

17.2 

i5-7 

14.7 

13-7 

8 

60. 

45- 

36. 

3»- 

25‘S 

22.5 

20. 

iS. 

l6.  I 

O' 

13.S 

12.S 

12. 

9 

53*3 

40. 

32- 

26.6 

22.9 

20. 

I7.s 

l6. 

H-5 

13-3 

12.3 

n.4 

IO.7 

10 

4S. 

36. 

2S.S 

-4* 

20.6 

iS. 

16. 

14.4 

i3-i 

12. 

I I . I 

IO.3 

9.6 

11 

43  6 

32-2 

26.2 

21.S 

■S  7 

16. 1 

H-5 

i3- ■ 

1 1. 9 

IO.9 

IO.I 

9-5 

8-7 

12 

4°. 

30- 

24. 

20. 

17.2 

15- 

13-3 

12. 

10.9 

IO. 

9.2 

S.6 

8. 

13 

36- 9 

27.7 

22.2 

1S.5 

1 5 • 7 

I3.S 

I2-3 

I I.  I 

10. 1 

9.2 

8-5 

7-9 

7-4 

14 

34-3 

25-7 

20.6 

17.2 

14.7 

I2.S 

11. 4 

10.3 

9-5 

S.6 

7-9 

7-4 

6.9 

15 

32- 

24’ 

19.2 

l6. 

13-7 

12. 

10.7 

9.6 

8-7 

S. 

7-4 

6.9 

6.4 

16 

30- 

22-5 

is. 

r5- 

12.9 

I 1 .2 

IO. 

9- 

S.2 

7-5 

6.9 

6.4 

6. 

17 

2S.2 

21.2 

16.9 

14. 1 

12. 1 

10.6 

9.4 

8-5 

7-7 

7- 

6.3 

6. 1 

5-6 

18 

26.6 

20. 

16. 

i3-3 

1 1 -5 

IO. 

S-9 

S. 

7-3 

6 6 

6.2 

5*7 

5 3 

19 

25*3 

1S.9 

i5-2 

12.6 

10. S 

9-5 

8-4 

7 6 

69 

6-3 

5-8 

5-4 

5-i 

20 

24- 

iS. 

14.4 

12. 

10.3 

9- 

S. 

7 2 

6-5 

6. 

5-5 

5-i 

4-8 

volume  of  8,750  cubic  feet  of  air  is  required  to  pass  through  a flue  at  a velocity 
of  900  feet  per  minute,  the  cross  sectional  area  of  that  flue  must  be  1,400  square 
inches.  The  greatest  difficulty  is  experienced  in  laying  out  a system  for  very 
small  rooms,  as  the  areas  required  become  relatively  minute  and  impracticable. 
Under  such  conditions,  it  is  wise  to  calculate  for  lower  velocities  than  usual,  so  as 
to  make  the  ducts  and  flues  of  manageable  size.  As  a rule,  a pipe  less  than 
5 inches  in  diameter,  or  a flue  less  than  8x8  inches,  should  be  avoided. 

Table  No.  9,  Of  the  Areas  of  Circles  and  of  the  Sides  of  Squares  of  the 
Same  Area,  will  be  found  to  be  of  service  in  all  such  calculations. 


57 


TABLE  No.  8. 

Flue  Area  Required  for  Given  Volume  and  Velocity. 


Volume  VELOCITY  IN'  FEET  PER  MINUTE. 


in  i,umc  reel 

per  Minute. 

300 

400 

500 

600 

700 

800 

900 

1000 

1100 

1200 

1300 

1400 

1500 

1600 

100 

48 

36 

29 

24 

21 

18 

16 

14 

13 

12 

11 

10 

9 6 

9. 

125 

6o 

45 

36 

3° 

26 

23 

20 

iS 

16 

>5  • 

>4 

>3 

12. 

>>■3 

150 

7-2 

54 

43 

36 

3' 

27 

24 

22 

20 

iS 

16 

>5 

>4.4 

>3  5 

175 

S4 

03 

5° 

42 

36 

32 

2S 

25 

23 

21 

>9 

iS 

16.S 

.5.8 

200 

96 

72 

58 

48 

41 

36 

32 

29 

26 

24 

22 

21 

19.2 

18. 

225 

ioS 

S. 

65 

54 

46 

4> 

3r> 

32 

29 

27 

2S 

23 

21  .6 

20.3 

250 

120 

90 

7 2 

60 

5' 

45 

40 

3<> 

33 

3» 

2S 

26 

24 

22-5 

275 

>32 

99 

79 

66 

57 

5° 

44 

40 

36 

33 

30 

2S 

26.4 

24.8 

300 

144 

108 

86 

72 

62 

54 

48 

43 

39 

36 

33 

31 

28.8 

27. 

325 

156 

1 17 

94 

7S 

67 

59 

S2 

47 

43 

39 

3^ 

33 

3>-2 

29-3 

350 

16S 

126 

IOI 

S4 

72 

63 

56 

5° 

46 

42 

39 

3<* 

33-6 

3>  -5 

375 

1S0 

■35 

10S 

90 

77 

6S 

60 

54 

49 

45 

42 

39 

3<5. 

33-8 

400 

192 

144 

115 

96 

82 

72 

64 

58 

52 

48 

44 

41 

38.4 

36. 

425 

204 

■53 

122 

102 

S7 

77 

6S 

6l 

S6 

5> 

47 

44 

40.  S 

3S.3 

450 

2l6 

l62 

'30 

10S 

93 

Si 

72 

6S 

59 

54 

5° 

46 

43  2 

40.5 

475 

22S 

>7' 

>37 

II4 

98 

So 

76 

6S 

62 

57 

53 

49 

45-6 

42.8 

500 

240 

180 

144 

120 

103 

90 

80 

72 

65 

60 

55 

51 

48. 

45. 

625 

252 

■89 

1 5 1 

126 

10S 

95 

S4 

76 

69 

6.3 

58 

54 

5°-4 

47-3 

550 

264 

19S 

■58 

>32 

"3 

99 

ss 

79 

72 

66 

6. 

57 

52  -s 

49-5 

575 

276 

207 

l66 

■38 

i iS 

><H 

92 

83 

75 

69 

64 

59 

SS-2 

S>-8 

600 

288 

216 

173 

144 

123 

108 

96 

86 

79 

72 

66 

62 

57.6 

54. 

625 

300 

225 

1S0 

■5° 

129 

> >3 

lOO 

90 

82 

75 

69 

64 

60. 

56.3 

650 

3>2 

234 

1S7 

'56 

>34 

1 '7 

IO4 

94 

Ss 

78 

7 * 

67 

62.4 

58.5 

675 

324 

243 

■94 

l62 

>39 

1 22 

10S 

97 

S8 

81 

75 

69 

64. S 

60.8 

700 

336 

252 

202 

168 

144 

126 

112 

101 

92 

84 

78 

72 

67.2 

63. 

725 

348 

26l 

209 

174 

>49 

1 3 ■ 

1 16 

IO4 

95 

87 

So 

75 

69.6 

*5-3 

750 

360 

270 

2"l6 

1S0 

>54 

>35 

120 

10S 

9S 

90 

S3 

77 

72. 

67-5 

775 

372 

279 

2-3 

1S6 

>59 

I4O 

124 

1 1 2 

IOI 

93 

86 

So 

74-4 

69.8 

800 

384 

288 

230 

192 

165 

144 

128 

115 

105 

96 

89 

82 

76.8 

72. 

825 

396 

297 

238 

198 

170 

>49 

>32 

i>9 

IO8 

99 

9> 

85 

79.2 

74-3 

850 

408 

306 

24S 

204 

>75 

>53 

*36 

1 22 

1 I I 

102 

94 

87 

S1.6 

76.5 

875 

420 

3*5 

2S2 

2IO 

1S0 

>58 

140 

126 

1 >5 

105 

97 

90 

S4. 

78.8 

900 

432 

324 

259 

216 

185 

162 

144 

130 

118 

108 

100 

93 

86.4 

81. 

925 

444 

333 

266 

2 22 

190 

'"7 

14S 

>33 

I 2 1 

I I I 

>°3 

95 

88.8 

83-  3 

950 

456 

34  2 

274 

22S 

>95 

l?1 

>52 

>37 

>24 

>>4 

>°5 

98 

91.2 

85-5 

975 

46S 

351 

2Sl 

234 

201 

176 

>56 

140 

I2S 

>>7 

IOS 

IOO 

93-6 

87.8 

1000 

480 

360 

288 

240 

206 

180 

160 

144 

131 

120 

111 

103 

96 

90. 

S8 


» VENTILATION  and  HEAT1NG« 

TABLE  No.  8 (Continued). 

I 

Flue  Area  Required  for  Given  Volume  and  Velocity. 


Volume 

In  Cubic  Feet 
per  Minute. 

VELOCITY  IN  FEET  PER  MINUTE. 

1700 

1800 

1900 

2000 

2100 

2200 

2300 

2400 

2600 

2700 

2800 

2900 

3000 

3100 

100 

8.5 

8 

7.6 

7.2 

6 9 

6.6 

6.3 

6. 

5 5 

5.3 

5.1 

5. 

4.8 

4 6 

125 

io.6 

10 

9-5 

9 

S.6 

8.2 

7.S 

7-5 

6.9 

6.7 

6.4 

6.2 

6. 

5-8 

150 

12.7 

12 

ii. 4 

10.S 

10.3 

9 S 

9-4 

9- 

S. 

S. 

7-7 

7-5 

7.2 

7- 

175 

14.S 

■4 

>3-3 

12.6 

12. 

ii-S 

I I. 

10.5 

9-7 

9 3 

9- 

S-7 

8-4 

S.i 

200 

16.9 

16 

15.2 

14  4 

13.7 

13.1 

12.5 

12 

11.1 

10.7 

10.3 

9.9 

9.6 

9.3 

225 

19. 1 

iS 

I?. 1 

l6.2 

15.6 

14.7 

14.1 

13-5 

>2-5 

I 2. 

1 1.6 

I 1.2 

10.$ 

IO.4 

250 

21.2 

20 

U). 

iS. 

1J . I 

16.4 

•S-7 

>5- 

>3-9 

3 

12  9 

12.4 

1 2. 

1 1 .6 

275 

2i  3 

23 

21. S 

19. s 

lS.9 

iS. 

17.2 

16.S 

IS-2 

14.7 

>4- 1 

>3-7 

>3-2 

■2.8 

300 

25  4 

24 

22  7 

21.6 

20.6 

19.6 

18  8 

18. 

16.6 

16. 

15.4 

14.9 

14.4 

13.9 

325 

27-S 

26 

24.6 

2 3 4 

22-3 

2I-3 

20.6 

>9-5 

iS. 

>7-3 

l6.7 

1 6.  i 

>5-6 

>5-» 

350 

29.6 

2$ 

26.5 

25  2 

24- 

22.9 

21  .9 

21. 

19.4 

>S.7 

iS. 

>7-4 

16. s 

16.3 

375 

3>-S 

3° 

2S.4 

27- 

25-7 

24-5 

23-5 

22.5 

20. S 

20. 

>9-3 

1S.6 

iS. 

17.4 

400 

33  9 

32 

30  3 

28.8 

27.4 

26.2 

25. 

24 

22  2 

21.3 

20.6 

19.8 

19.2 

18.6 

425 

36. 

34 

32.2 

30  6 

29.1 

27.S 

26  6 

25-5 

23-5 

22  7 

21.9 

21. 1 

20.4 

19.7 

450 

36 

34-1 

32-4 

3°-9 

29*S 

2S  2 

27. 

24.9 

24* 

23.  1 

22.3 

21.6 

20.9 

475 

40.2 

38 

36- 

34-2 

3.2.6 

31- 1 

29.7 

2S.5 

26.3 

25*3 

24.4 

23.6 

22. S 

22.1 

500 

42.4 

40 

37.9 

36. 

34.3 

32.7 

31.3 

30 

27  7 

26.7 

25.7 

24.8 

24. 

23.2 

525 

44-5 

42 

39  S 

37  S 

36. 

34-4 

3 2 9 

3 1 -5 

29.1 

2S. 

26.9 

2S- 

25.2 

24.4 

550 

46  6 

44 

4 1 -7 

3S6 

37-7 

36- 

34-4 

33- 

30-5 

29-3 

2S-3 

27-3 

26.4 

25-5 

575 

4S.7 

46 

43  6 

4 1 - 4 

39-4 

376 

3<5- 

34-5 

3>-9 

30-7 

29.6 

2S  5 

27.6 

26.7 

600 

50  8 

48 

45.6 

43.2 

41  1 

39  3 

37.6 

36. 

33  2 

32. 

30.8 

29.8 

28.8 

27.8 

625 

52-9 

So 

47-4 

45* 

42.9 

40.9 

39- 1 

37*5 

34-6 

33-3 

32-1 

3>- 

3°- 

29- 

650 

5S-> 

S 2 

49-3 

46.S 

44.6 

42-5 

4°  7 

39- 

36- 

34*7 

33-4 

32-2 

3>-2 

30.2 

675 

SI-2 

54 

5>-2 

4S.6 

46-3 

44-i 

42-3 

4° -5 

37-5 

36 

34-7 

33  5 

32-4 

3 1 -3 

700 

59.3 

56 

53.1 

50.4 

48. 

45  8 

43  8 

42. 

38.8 

37.3 

36. 

34.7 

33.6 

32.5 

725 

61.4 

ss 

55* 

52.2 

49  7 

47-4 

45  4 

43*5 

40.2 

3S.7 

37-3 

36. 

34-S 

33-6 

750 

63  s 

60 

S6-9 

54- 

5 1 - 4 

49.1 

47- 

45- 

41.5 

40. 

3S.6 

3 7-2 

3<>- 

34-8 

775 

65.6 

62 

5S.S 

56.3 

S3-1 

So- 7 

4S.5 

46-5 

42-9 

4>-3 

39-9 

3S.S 

37-2 

3<5- 

800 

67  8 

64 

60.6 

57.6 

54  9 

52.4 

50.1 

48. 

44.3 

42.7 

41.2 

39.7 

38.4 

37.1 

825 

69.9 

66 

62.5 

59- 4 

56  6 

54* 

5 1 - 7 

49-5 

45-7 

44 

42.4 

4°.  9 

39-6 

3S.3 

850 

72- 

6S 

64.4 

6l.2 

SS*4 

55-6 

S3-2 

S'- 

47.1 

45-3 

43*7 

42.2 

40.  s 

39-4 

875 

74- 

7° 

67-3 

63- 

60. 

57*3 

54-S 

52-5 

4S.5 

46.7 

45- 

43-4 

42. 

40.6 

900 

76  2 

72 

68.2 

64.8 

61.7 

58.9 

56  3 

54. 

49.9 

48 

46.3 

44.6 

43.2 

41.8 

925 

7S.4 

74 

70.1 

65.6 

634 

60.5 

57-9 

55-5 

5 1 • 3 

49-3 

47-6 

46. 

44-4 

42.9 

950 

S0.5 

76 

72. 

6S.4 

65.1 

62.2 

59-5 

57* 

52.6 

50-7 

4S.S 

47.1 

4S-6 

44.1 

975 

S2.6 

7S 

73  9 

70.2 

66  S 

63.  S 

6l  .O 

5®  5 

54- 

52- 

5°-2 

4S.4 

46. s 

45-3 

1000 

84.7 

80 

75.8 

72. 

68  7 

66. 

62  6 

60. 

55.4 

53  3 

51.4 

49  6 

48. 

46.4 

59 


» VENTILATION  and  HEAT1NG« 

TABLE  No.  9. 

Of  the  Areas  of  Circles  and  of  the  Sides  of  Squares 

of  the  Same  Area. 


Diam.  ot 

Area  of  Circle 

Sides  of  Sq.  of 

Diam.  of 

Sides  of  Sq.  of 

Diam.  of 

Area  of  Circle  | 

Sides  of  Sq.  of 

Circle 
in  inches. 

in  square  ms. 

same  area 
in  square  ins. 

Circle 
in  inches. 

in  square  ms. 

same  area 
in  square  ms. 

Circle 
in  inches. 

in  square  ins. 

same  area 
in  square  in«. 

1. 

•7§S 

.89 

21. 

346.36 

1S.61 

41. 

1320.26 

3634 

■'/2 

1.767 

J-33 

■X 

36305 

19.05 

■X 

1352  66 

36.78 

2. 

3-142 

1.77 

22. 

38013 

19.50 

42. 

I385-45 

37-22 

■X 

4.909 

2.22 

■X 

397-6i 

19  94 

■X 

1418.63 

37.66 

3. 

7.069 

2.66 

23. 

415-48 

20.38 

43. 

1452.20 

38.11 

■X 

9.621 

3.10 

■X 

433-74 

20.  S3 

■X 

1486.17 

38.55 

4. 

12.566 

3-54 

24. 

452-39 

21.27 

44. 

1520.53 

38-99 

•X 

15-9°4 

3-99 

. *4 

471-44 

21.71 

■X 

I555-29 

39-44 

5. 

i9-63S 

4 4 .3 

25. 

490. S8 

22. 16 

45. 

i59°-43 

39.  S8 

I ' 

*/2 

23-7S3 

4.87 

510.71 

22.60 

■X 

1625.97 

4032 

6. 

28  274 

5- 32 

26. 

530  93 

2304 

46. 

1661.91 

4°-77 

33  183 

5-76 

55 1 -55 

23  49 

1 x 

1698.23 

41.21 

7. 

38-485 

6.20 

27. 

572-56 

2.3-93 

47. 

1734-95 

41-65 

•X 

44- *79 

6.65 

•X 

593-96 

24-37 

■X 

1772.06 

42.10 

8. 

50.266 

7.09 

28. 

6i5-75 

24.81 

48. 

1S09.56 

42-58 

•X 

56-745 

7-53 

•la 

637  94 

25-26 

■X 

1S47.46 

42.98 

9. 

63.617 

7.98 

29. 

660.52 

25-70 

49. 

ISS5-75 

43-43 

■X 

70.SS2 

8.42 

•. X 

6S3.49 

26. 14 

■X 

192443 

-13-87 

10. 

78  540 

S.S6 

30. 

706.  S6 

26.59 

50. 

1963.50 

44-31 

■X 

86.590 

9-30 

■X 

730.62 

27.03 

2002.97 

44-75 

li. 

95  03 

9 75 

31. 

754-77 

27-47 

51. 

204 2. S3 

35-20 

103.87 

IO.  I9 

. *4 

779  3i 

27.92 

■X 

20S3.08 

4564 

12. 

1 13- 10 

10.63 

32. 

S04.25 

28.36 

52. 

2123.72 

46.08 

■X 

122.72 

11.08 

■X 

829.58 

28.80 

2164.76 

46  53 

h-* 

CO 

132-73 

11.52 

33. 

855-30 

29  25 

53. 

2206.19 

46.97 

•X 

I43-I4 

11.96 

•X 

881.41 

29.69 

•X 

2248.01 

47  4i 

14. 

2.53-94 

12.41 

34. 

907.92 

30-13 

54. 

2290.23 

27.86 

48.30 

•>2 

165-13 

12.85 

1/ 

*/- 

934.82 

30-57 

2332.83 

15. 

176.72 

13-29 

35. 

962.11 

31.02 

55. 

2375-83 

48.74 

18S.69 

13-74 

1/ 

•/2 

9S9.80 

3i-46 

2419-23 

49.19 

16. 

201.06 

14.18 

36. 

1017. 8S 

31.90 

56. 

2463.01 

49-63 

•X 

213-S3 

14.62 

1046.35 

32-35 

•X 

2507.19 

50.07 

17. 

226.98 

15-07 

37. 

1075.21 

32.79 

57. 

; 2551.76 

50-51 

■X 

240-53 

15-5 1 

■X 

1104.47 

33-23 

•K 

2596-73 

50.96 

18. 

2.54-47 

15  95 

38. 

H34.12 

33-68 

58. 

2642.O9 

5I-4° 

■X 

268.80 

16.40 

■X 

1 164.16 

34-12 

■X 

26S7.84 

51.84 

19. 

CO 

Ui 

CO 

CO 

C4 

16.84 

39. 

H94-59 

34-56 

59. 

2733.98 

52-29 

298.65 

17.2S 

1225.42 

35-oi 

•K 

27S0.5I 

52-73 

20. 

314.16 

17.72 

40. 

1256  64 

35-45 

60. 

2827.74 

53-17 

■X 

330.06 

18.17 

■X 

12S8.25 

35-89 

l/ 

*/- 

2874-76 

53-62 

60 


WEIGHT  OF  GALVANIZED  IRON  PIPE.  As  already  stated,  galvan- 
ized iron  is  almost  exclusively  employed  for  the  making  of  large  pipes,  ducts  and 
tines  for  the  conduction  of  warm  air.  Its  non-rusting  qualities,  and  the  large 
size  of  the  sheets  in  which  it  may  he  purchased,  make  it,  by  all  means,  the  best 
suited  material  for  this  purpose.  Although  straight,  round  pipe  is  frequently 
sold  by  the  running  foot,  the  ordinary  practice  in  work  at  all  complicated,  as  in 
the  case  of  a heating  and  ventilating  system,  is  to  base  the  price  upon  the  weight, 
the  rate  being  at  a given  amount  per  pound.  As  prices  have  to  be  made  in 
advance,  it  is  evidently  very  necessary  that  one  should  be  able  to  accurately 
estimate  with  comparative  ease  from  a drawing  the  amount  of  material  required. 

To  aid  in  such  calculations  Table  No.  10  has  been  prepared,  giving  not  only 
#the  weight  of  the  galvanized  iron  per  square  foot,  but  also  the  weights  per 
running  foot  for  round  pipe  and  the  weight  of  elbows  of  corresponding  sizes. 
This  table  may  be  relied  upon  as  giving  the  maximum  weight,  due  allowance 
having  been  made  for  laps  and  trimmings,  as  well  as  for  rivets  and  solder ; the 
general  waste,  for  obvious  reasons,  cannot  be  included.  The  elbows  are  of  the 
standard  type  previously  described,  having  the  internal  radius  of  curvature  equal 
to  the  diameter  of  the  pipe  itself.  All  of  the  weights  are  based  upon  the 
recently-adopted  schedule  of  galvanized  iron,  in  which  the  weights  per  square 
foot  to  some  extent  vary  from  those  previously  existing. 

In  ordinary  heating  and  ventilating  practice,  it  is  customary  to  make  round 
pipe  in  its  various  sizes  upon  gauges  as  follows:  under  9 inch,  No.  28  gauge  ; 
9 to  14  inch,  No.  26;  15  to  20  inch,  No.  25  ; 21  to  26  inch,  No.  24;  2 7 to 
35  inch,  No.  22;  36  to  46  inch,  No.  20;  47  to  60  inch,  No.  18;  and  all  sizes 
above  60  inch  of  No.  16  gauge.  If  the  pipe  is  made  much  lighter,  particularly 
in  the  larger  sizes,  it  will  not  keep  its  shape  when  laid  horizontally,  thereby 
seriously  affecting  the  tightness  of  the  joints  and  decreasing  the  area. 

The  common  practice  is  to  make  rectangular  pipes  of  the  same  gauge  as 
round  pipes  having  an  equivalent  area,  but  under  certain  conditions,  as  in  the 
case  of  thin,  flat  pipe  for  overhead  distribution  in  a basement,  bracing  is  necessary 
to  prevent  the  top  and  bottom  from  sagging  even  with  heavy  gauges.  There- 
fore, with  the  bracing,  gauges  lighter  than  the  ordinary  may  be  used. 

In  calculating  the  weight  of  rectangular  pipe,  its  superficial  area,  i.e.,  its 
perimeter  in  feet,  multiplied  by  its  length  in  feet,  is  taken  as  the  basis,  and 
special  shapes  are  figured  in  a similar  manner.  The  laps  in  rectangular  pipe 
require  more  stock  than  in  round  pipe,  and,  therefore,  from  ten  to  twenty-five 
per  cent,  is  added,  according  to  the  character  of  the  pipe,  to  allow  for  this  excess 
of  material  and  for  the  weight  of  the  necessary  bracing  and  ribbing. 


61 


TABLE  No.  10. 


Of  the  Weight  of  Round  Galvanized  Iron  Pipe 

and  Elbows. 


Gauge 
and  Wt. 
per 

Sq.  Ft. 

Diam. 

of 

Pipe. 

Area 

in 

Sq.  Ins. 

Weight 

per 

Running  Ft. 

Weight 

of 

Full  Elbow. 

3 

7-i 

0.7 

0.4 

4 

12.6 

1. 1 

0 9 

No.  28 

5 

19.6 

1.2 

1 .2 

0.7S 

6 

2S.3 

i-4 

i-7 

/ 

3$-5 

i-7 

2-3 

S 

50.3 

1.9 

2.9 

9 

63.6 

2.4 

4 3 

IO 

7^-5 

2.7 

5-3 

No.  26 

I I 

95-° 

2.9 

6.4 

O.9I 

12 

”3-i 

3-2 

7.6 

'3 

13^7 

3-4 

8-9 

•4 

1 S3 -9 

3*7 

10.4 

IS 

176.7 

4-5 

13-5 

l6 

201.  I 

4-7 

i5- 1 

No.  25 

17 

227.0 

5-° 

17.0 

1.03 

iS 

254-5 

5-3 

19. 1 

!9 

-’83-5 

5-6 

21.4 

20 

314-2 

6.0 

23-9 

21 

346-4 

7.0 

29.6 

380.1 

7-3 

32-3 

No.  24 

23 

4 1 5 -5 

7 7 

35-6 

1. 16 

-4 

4S2-4 

S.o 

3S.6 

2 5 

490.9 

8-3 

4i-7 

26 

53°  9 

S-7 

45  1 

-7 

572.6 

IO.9 

59- 1 

2S 

6i5-7 

11  4 

64.2 

29 

660.5 

11  S 

6S.6 

No.  22 

30 

706.9 

12.2 

73-4 

3 1 

754-8 

12.6 

7S3 

1.41 

32 

804-3 

13.0 

83-4 

33 

855-3 

13-5 

8S.9 

34 

907.9 

13  9 

94-3 

35 

962.1 

14-3 

99.9 

No.  20 

36 

1017.9 

17.2 

124.4 

1.66 

37 

1075.2 

17  S 

131  4 

Gauge 
and  Wt. 

! Diam. 
of 

Area 

in 

Weight 

per 

Weight 

of 

Sq,  Ft, 

Pipe. 

Sq.  Ins. 

Running  Ft. 

Full  Elbow. 

38 

H34-I 

1S.2 

139-4 

39 

1194.6 

1S.7 

146.0 

40 

1256.6 

19.1 

152-9 

No.  20 

41 

1320.3 

19.6 

160.7 

42 

i3s5-4 

20. 1 

16S.6 

1.66 

43 

1452.2 

20.6 

176.7 

44 

'520.5 

21.0 

'85.0 

45 

1.590-4 

21-5 

193-4 

46 

1661.9 

22.0 

202.2 

47 

1734-9 

29.2 

274-3 

4s 

1S09.6 

29.8 

286.6 

49 

iSSs-7 

30  4 

298.8 

5° 

1963-5 

31.0 

309-9 

5i 

2042. s 

31.6 

322  5 

No.  18 

5- 

53 

2I23-7 

2206.2 

32- 2 

33- o 

335-1 

349-7 

2.  l6 

54 

2290.2 

33-6 

363  4 

55 

2375-8 

34-4 

377  - 2 

56 

2463.0 

34-9 

390-7 

57 

255i-8 

35-6 

405-1 

58 

2642. 1 

36.1 

41S.8 

59 

2734-0 

36-7 

433-1 

60 

2827.4 

37-4 

44S.6 

61 

2922.5 

46.7 

569-7 

62 

3019. 1 

47-5 

5S9.0 

63 

3ii7-3 

48-3 

60S.6 

64 

3217.0 

49.1 

628.5 

No.  16 

65 

3318.3 

49.8 

647.4 

66 

3421.2 

50-5 

666.6 

2.66 

67 

3525-7 

5'-3 

6S7.4 

68 

3631-7 

52.1 

70S. 6- 

69 

3739-3 

52.8 

72S.6 

70 

3S48-5 

53-6 

750-4 

7i 

3959-2 

54-3 

771.0 

l2 

4071-5 

55-i 

793-4 

62 


^VENTILATION  and  HEATING ©S 


MIXING  DAMPERS.  With  the  advent  of  the 
hot  and  cold  or  double  duct  system  there  arose  the 
necessity  of  a simple  contrivance  to  coincidently 
regulate  the  volume  of  air  discharged  from  the  two 
ducts.  Two  methods  of  regulation  appear:  first, 
that  by  which  full  volumes  of  cold  air  and  of  warm 
air  are  alternately  admitted ; and  second,  that  by 
which  a damper  is  so  constructed  and  adjusted 
as  to  permit  the  air  of  the  two  temperatures 
to  produce  a constant  mixture  of  the  desired 
temperature.  If,  by  the  first  method,  the 
alternations  are  sufficiently  rapid,  the  room 
is  maintained  at  practically  a constant  tem- 
perature, but  if  less  frequent  the  tendency 
is  toward  fluctuation  between  extremes, 
although  the  proper  average  may  be  main- 
tained. 

Obviously,  the  first  type  of  damper  is 
impracticable  for  operation  by  hand,  for  it 
would  require  constant  attention.  For  hand 
regulation  the  second  type  must,  therefore,  be  adopted  ; and,  for  perfect  action, 
it  must  so  admit  the  air  volumes  relatively  to  each  other,  that  one  shall  be 
decreased  proportionally  as  the  other  is  increased,  and  thus  cause  the  volume  to 
continue  constant.  This  requirement  is  met  in  the  Sturtevant  mixing  damper, 
which,  being  of  cylindrical  form,  of  necessity  fulfils  this  function.  As  ordinarily 
arranged  for  hand  regulation,  it  is  shown  in  Fig.  1 1,  in  connection  with  a system 
of  overhead  ducts  suspended  just  below  the  basement  ceiling.  The  damper 
proper  swings  in  a cast  iron  frame,  which  may  be  bricked  into  the  wall,  and  to 

which  the  double  system  of  ducts  may  be  con- 
nected. From  the  cylinder,  which  is  pivoted 
as  shown,  there  extends  up  the  flue  a chain, 
which,  after  passing  over  a guide  pulley,  is 
conducted  into  the  room  at  some  three  or  four 
feet  above  the  floor,  there  to  be  operated  at 
the  will  of  the  occupants. 

When  the  air  is  conducted  beneath  the 
basement  floor,  the  arrangement  of  ducts  and 
damper  is  as  shown  in  Fig.  12.  Under  these 


Fig.  11. 


) 


63 


VENTILATION  and  HEATING 


conditions  proper  manholes  should  be 
provided  to  permit  of  access  to  the  ducts. 

Although  the  temperature  of  a given 
apartment  may,  by  such  means,  be  main- 
tained very  near  a stated  temperature, 
the  mixing  damper  may,  under  certain 
conditions,  require  such  attention  that 
the  desirability  of  some  other  than 
human  agency  may  seem  desirable  for  its  operation. 
This  part  is  played,  and  most  perfectly  too,  by  the 
thermostat,  which,  operating  under  the  influence  of 
the  variations  in  temperature  of  the  room,  acts  to 
produce  converse  action  of  the  mixing  damper.  That  is,  as  the  room  tempera- 
ture increases,  the  volume  of  cold  air  admitted  is  increased,  while  the  warm  air 
is  correspondingly  decreased. 

When  regulation  of  temperature  is  to  be  secured  by  a maintained  mixture 
of  the  hot  and  cold  air,  the  type  of  damper  previously  illustrated  is  employed. 
In  Fig.  13  is  represented  such  a damper  operated  gradually  by  a thermostat, 
acting  through  a system  of  levers.  With  such  a type  of  damper,  it  is  possible 
to  supply,  through  the  cold  air  duct,  air  that  has  acquired  no  heat  other  than  that 
taken  up  in  its  passage  through  the  duct  to  the  damper.  But,  if  so  supplied,  the 
damper  must  be  capable  of  shutting  it  off  com- 
pletely, if  occasion  demands  that  a full 
supply  of  hot  air  only  shall  be  delivered 
to  the  room  to  maintain  the  desired 
temperature.  This  is  attained  in 
the  Sturtevant  mixing  dampers  by 
packing  the  cylinder  with  felt  in 
such  a manner  as  to  prevent  all 
leakage  of  cold  air  when  closed 
against  its  supply. 

For  intermittent  operation  the 
type  of  damper  shown  in  Fig.  14 
is  frequently  employed.  This  consists 
mereiy  of  two  straight  butterfly  dampers 
set  at  right  angles  to  each  other,  so  that 
when  one  is  closed  the  other  is  open.  Natu- 
rally with  a damper  of  this  description, 


» 


Fig.  14. 


64 


operating  to  alternately  admit  cold  and  warm  air,  the  relative  temperature 
of  the  cold  air  should  be  only  a little  below  that  of  the  room  to  which  it  is 
supplied,  for  otherwise  too  sudden  cooling  and  objectionable  draughts  would  be 
caused.  It  is,  therefore,  necessary  under  these  conditions  to  provide,  in  con- 
nection with  the  main  apparatus,  a tempering-coil  through  which  all  of  the 
air  shall  pass,  and  from  which  volume  the  supply  for  the  so-called  cola-air 
duct  shall  be  taken. 

A damper  of  this  type  is  not  desirable  for  gradual  adjustment  where  a 
constant  mixture  is  maintained ; tirst,  because  it  is  inherently  incapable  of  keeping 
the  total  volume  constant  with  the  varying  relative  volumes  of  hot  and  cold  air; 
and  second,  because,  as  ordinarily  constructed,  it  does  not  shut  tight  against  the 
cold  air  supply. 

ADVANTAGES  OF  THE  STURTEVANT  SYSTEM.  The  advantages  of 
the  Sturtevant  System,  although  incidentally  mentioned  in  the  preceding  pages, 
may  here  be  summarized  under  two  main  heads : 

First,  adaptability  and  convenience. 

Second,  efficiency  and  economy. 

The  early  consideration  of  the  system  before  the  plans  of  the  building  are 
completed  has,  of  course,  much  to  do  with  its  adaptability  and  the  convenience 
with  which  it  may  be  introduced. 

The  centralizing  of  the  entire  heating  surface  in  a single  room  and  within  a 
single  sheet-iron  jacket  avoids  all  danger  by  tire,  prevents  the  possibility  of 
damage  by  leakage,  and  removes  all  anxiety  regarding  the  freezing  incident  to 
isolated  coils.  A single  valve  serves  to  control  the  temperature  of  all  air 
admitted  to  the  building,  so  that  the  thoroughly  installed  system,  with  its 
governed  engine,  self-oiling  devices,  automatic  return  water  apparatus,  damper 
regulator,  and  its  thermostatic  control,  is  rendered  so  completely  self -controlling 
that  the  attendant’s  care  is  usually  reduced  to  supplying  sufficient  coal  to 
the  boiler. 

The  system  is  positive  in  its  action  at  all  times,  the  air  is  put  where  it  is 
wanted,  not  merely  allowed  to  go.  The  pressure  created  within  the  building  is 
sufficient  to  cause  all  leakage  to  be  outward,  preventing  cold  inward  draughts 
and  avoiding  the  possibility  of  drawing  air  from  any  polluting  source  within  the 
building  itself. 

Absolute  control  may  be  had  over  the  quality  and  quantity  of  air  supplied. 
It  may  be  filtered  and  cleansed,  heated  or  cooled,  dried  or  moistened  at  will.  By 
means  of  the  hot  and  cold  mixing  damper,  the  temperature  of  air  admitted  to 
any  given  apartment  may  be  instantly  and  radically  changed. 


VENTILATION  and  HEATING 


The  efficiency  and  economy  of  the  system  must  of  necessity  be  considered 
under  first  cost  and  running  expense. 

Circumstances  so  decidedly  alter  cases  that  an  arrangement  economical  and 
easy  of  introduction  in  one  building  may  prove  very  expensive  in  another.  In 
most  cases,  however,  the  Sturtevant  System,  regarded  simply  as  a method  of  heat- 
ing, may  be  installed  for  less  money  than  any  other  system  of  equal  efficiency. 
Wherever  the  flues  can  be  formed  in  the  walls  and  the  distributing  ducts 
are  of  moderate  extent,  the  system  will  figure  less  in  first  cost  than  any  other 
capable  of  attaining  the  same  results  and  of  supplying  the  same  amount  of  air. 
The  primary  cost  of  a fan  is  less  than  that  of  any  other  device  for  moving  the 
same  amount  of  air. 

The  large  volume  of  air  passing  through  the  heater  causes  a condensation  of 
steam  so  great  that  one  foot  of  heating  surface  is  rendered  the  equivalent  in 
efficiency  of  three  to  five  feet  in  the  form  of  the  ordinary  direct  radiator 
exposed  in  the  room.  This  saving  in  heating  surface  offsets  the  additional  cost 
of  fan  and  motor.  As  bearing  directly  upon  this  point,  Professor  Woodbridge* 
has  stated  with  regard  to  the  installation  in  the  Walker  Building,  of  the  Mass. 
Institute  of  Technology,  that  the  saving  in  piping  due  to  rapid  condensation  in 
the  coils,  as  there  arranged,  was  sufficient  to  pay  for  the  fan,  as  well  as  an 
attached  engine,  had  the  latter  been  adopted. 

In  all  fairness,  the  operating  expenses  of  any  system  must  be  compared 
upon  a basis  of  similar  conditions.  The  Sturtevant  System,  when  taking  its  air 
from  out-of-doors,  cannot  be  properly  compared  with  any  system  of  direct 
radiation,  for  in  the  latter  is  lacking  the  advantage  of  the  ventilation  incidental 
to  the  operation  of  the  former.  But  when  the  Sturtevant  System  rehandles  and 
reheats  the  air  within  the  building  without  outside  supply,  the  comparison 
becomes  more  reasonable,  although  there  will  still  continue  to  be  a considerable 
change  of  air  due  to  leakage. 

A six  months’  continuous  test  at  the  Globe  Yarn  Mills,  Fall  River,  has 
presented  data  exceptionally  valuable  for  comparison,  as  indicated  in  the  accom- 
panying record  for  the  period  October  15,  1888,  to  March  15,  1889: 


Mill  No.  i. 

Mill  No.  2. 

Average  temperature 

70° 

78° 

Coal  burned  for  heating 

Coal  burned  for  heating,  ventilating  and  moistening  . 

317,000  lbs. 

286,900  lbs. 

Coal  burned  per  l ,000  cubic  feet  of  space  . 

340.26  lbs. 

217.92  lbs. 

Ratio 

t 100 

64 

\ 156 

100 

♦Technology  Quarterly,  Vol.  II.  No.  i. 


66 


Mill  No.  1 was  heated  by  direct  steam,  with  overhead  pipes.  Mill  No.  2, 
which  stood  beside,  and  contained  212,668  cubic  feet  more  than  Mill  No.  1,  was 
equipped  with  the  Sturtevant  System.  It  is  to  be  noted  that  in  the  mill  heated 
by  the  Sturtevant  System,  a temperature  of  78°  was  maintained  as  against  70° 
in  the  other  mill,  while  the  total  amount  of  coal  consumed  for  its  threefold 
duty  of  heating,  ventilating  and  moistening  was  only  sixty-four  per  cent,  of  the 
cost  of  merely  heating  the  other  mill. 

The  cost  of  janitorial  service  enters  as  an  important  factor  in  any  building 
other  than  a manufactory.  The  Sturtevant  System  has  been  adversely  criticised 
because  of  the  experience  required  in  its  operation.  In  point  of  fact,  it  has  been 
attempted  by  committees  and  school  boards  to  place  the  control  of  the  system 
in  the  hands  of  men  who  could  sweep  floors  and  shovel  coal,  but  scarcely  knew 
the  difference  between  a boiler  and  an  engine.  It  is  not  greater  intelligence,  but 
a different  order  of  intelligence,  that  is  required. 

When  exhaust  steam  that  would  otherwise  be  thrown  away  is  utilized 
in  the  heater,  its  cost  must  be  considered  as  practically  nothing.  The  condensa- 
tion in  the  heater  of  all  the  exhaust  steam  from  the  special  fan  engine  reduces 
the  cost  for  motive  power  to  a minimum. 

As  to  comparisons  regarding  cost  of  repairs,  much  may  be  said  pro  and 
con ; but  the  character  of  the  machinery,  its  few  parts,  slow  speed  of  engine 
and  fan,  the  sectional  construction  of  the  heater,  the  lack  of  complication  of 
valves,  the  concentration  of  the  plant  at  one  point,  and  the  fact  that  it  is  under 
the  care  of  one  man,  are  greatly  in  its  favor. 

THE  DESIGN  OF  HEATING  AND  VENTILATING  SYSTEMS.  It 
must  appear  from  the  preceding  pages  that  the  proper  design  of  a satisfactory 
system  of  heating  and  ventilation  is  no  simple  matter.  It  is  neither  a question 
of  theory  nor  of  practice,  the  one  independent  of  the  other,  but  such  a com- 
prehensive knowledge  of  the  entire  matter  is  necessary  that  certainty  of  result 
may  be  assured.  As  the  demands  for  improved  ventilation  have  increased,  the 
problem  has  grown  more  and  more  complicated  until  it  has  become  an  evident 
fact  that  no  public  building  of  reasonable  size  should  be  trusted  to  other  than  an 
expert  of  established  reputation. 

As  a consequence,  the  architect  looks  either  to  an  expert  engineer,  or  to  a 
reputable  and  experienced  house,  to  develop  the  plans  for  the  heating  and 
ventilation.  The  B.  F.  Sturtevant  Co.  has  now  been  directly  connected  with 
this  class  of  work  for  nearly  a third  of  a century,  has  fostered  and  established 
the  general  system  of  heating  and  ventilation  by  a forced  circulation  of  warm 


VENTILATION  and  HEATING 


air,  and  stands  to-day  in  the  fore-front  of  those  who  are  prepared  and  qualified 
to  undertake  the  largest  contracts  wherein  the  fan  is  an  essential  feature.  The 
Sturtevant  System  has  been  upheld  because  it  is  theoretically,  logically  and 
practically  the  best , and  the  sincere  desire  of  this  house  has  always  been  that  the 
System  should  win  upon  its  merits.  The  extensive  business  of  to-day  certainly 
testifies  to  the  fact  that  such  has  been  the  case. 

The  B.  F.  Sturtevant  Co.  solicits  inquiry  from  all  parties  interested  in 
improved  methods  of  heating  and  ventilation  ; it  cheerfully  furnishes  complete 
plans  and  specifications  for  all  buildings  whose  character  would  warrant  the 
introduction  of  the  System,  and  is  prepared  to  take  contracts,  under  its  own  or 
others’  specifications,  for  any  portion  or  the  whole  of  the  work  of  heating  and 
ventilating  where  a fan  is  employed. 


68 


VENTILATION  and  HEATING* 


THE  STURTEVANT 


HEATING  AND  VENTILATING  APPARATUS. 


PON  the  pages  immediately  following  are  presented,  in  as  concise  form  as 


u possible,  descriptions  and  illustrations  of  the  more  important  and  charac- 
teristic types  of  apparatus  manufactured  by  this  house  for  the  purposes  of 
heating  and  ventilation.  Special  types  and  more  detailed  descriptions  will  be 
found  in  other  catalogues  published  by  this  Company,  and,  wherever  necessary, 
special  designs  will  be  furnished. 

The  component  parts  of  the  Sturtevant  Heating  and  Ventilating  Apparatus 
are  a Fan  Wheel,  enclosed  or  not  as  best  suits  the  circumstances,  and  arranged  to 
be  driven  either  by  belt  or  by  direct  connection  by  means  of  some  form  of 
motor,  preferably  a Steam  Engine  or  Electric  Motor ; a Steam  Heater,  across 
which  the  air  is  forced  or  drawn ; and  a Return  Water  Apparatus,  consisting  of  a 
steam  trap  or  of  a pump  and  receiver  arranged  to  operate  automatically. 


FANS. 


THE  FAN  WHEEL.  As  constructed  for  ordinary  ventilating  purposes, 
the  fan  wheel  consists  of  a series  of  T steel  arms  cast  into  a hub  and  carrying 
the  floats  or  blades,  which,  together  with  the  side  plates  of  the  wheel,  are  con- 
structed of  light  but  strong  steel  plate,  substantially  as  shown  in  Fig.  15.  Here, 
as  is  the  case  with  all  wheels  above  the  smaller  sizes,  two  hubs  are  used.  This 
construction  combines  the  minimum  of  weight  with  the  maximum  of  strength 
and  durability,  and  is  especially  designed  to  meet  the  requirements  of  a ventilat- 
ing fan,  namely,  ability  to  handle  the  largest  volumes  of  air,  at  low  pressure, 
with  the  least  expenditure  of  power.  The  wheel  is  carried  by  a stiff  steel  shaft 
supported  in  the  Sturtevant  patent  brush  oiler  boxes.  Constructed  with  the 
greatest  care,  of  the  best  materials,  and  containing  an  oil  reservoir  from  which 
the  oil  is  continuously  fed  to  the  journal  by  the  brushes,  this  box  is  at  once 
unbeatable , is  capable  of  universal  adjustment,  and  once  tilled  with  oil  may  be 
run  for  weeks  without  further  attention. 


69 


VENTILATION  and  HEATING 


Although  this  type  of  fan  may 
be  used  without  a casing  where 
properly  arranged  in  connection 
with  a supply  opening,  it  is 
almost  universally  employed 
wherever  the  wheel  is  to  be 
encased,  whether  in  sheet 
metal,  brick  or  wood. 

Evidently  a sheet  metal 
casing  may  be  almost  as 
readily  constructed  in  one 
form  as  another,  so  that 
all  locations  of  discharge 
are  possible,  and  complete 
steel  plate  housings  may 
be  readily  made  to  conform 
to  given  and  special  designs. 

As  ordinarily  built,  either  to  be 
driven  by  pulley  or  by  direct 
connected  engines,  these  various 
shapes  of  housings  are  illustrated  on 
subsequent  pages. 


Fig.  15.  Fan  Wheel. 


DISC  WF1EEL.  When  air  is  to  be  moved  against  very  slight  resistance, 
as  is  the  case  where  exhaust  ventilation  is  to  be  accelerated,  the  disc  or  propeller 
form  of  wheel,  as  illustrated  in  Fig.  16,  is  of  great  service.  This  wheel,  light  in 
its  construction,  consuming  but  little  power  at  low  speeds,  and  very  easily 
erected,  is  exceedingly  convenient  for  introduction  in  the  attic  or  upper  story  of 
a building,  where  it  may  be  driven  by  belt  from  an  adjacent  electric  motor. 
Under  such  an  arrangement,  it  is  usually  installed  at  the  junction  of  the  connec- 
tions from  the  ventilating  flues  in  such  a manner  that  when  not  in  operation 
there  is  very  little  obstruction  offered  to  the  flow  of  air  by  natural  means. 

For  certain  locations  this  fan  is  fitted  with  a special  type  of  horizontal 
engine,  as  shown  in  Fig.  17,  readily  installed  uppn  a projecting  shelf.  Thus 
arranged  it  may  be  employed  as  a plenum  fan,  to  force  air  into  a building.  But 
great  discretion  should  be  exercised  in  its  introduction  for  such  a purpose,  for  it 
lacks  ability,  except  at  excessive  expenditure  of  power,  to  force  air  through  a 
complicated  system  of  distributing  ducts. 


70 


CONE  FAN.  Wherever  a fan  wheel  is  to  be  used  without  casing  and 
under  conditions  that  require  anything  above  the  most  moderate  air  pressure, 
the  cone  fan  is  particularly  desirable.  As  ordinarily  installed,  it  is  placed  close 
up  to  a division  wall  in  which  is  located  an  inlet  opening  concentric  with  the 
inlet  of  the  wheel.  The  air  is  thus  drawn  from  one  side  of  the  wall  and 
delivered  into  a space  of  greater  or  lesser  extent  upon  the  other  side,  where  the 
fan  is  located.  As  ordinarily  constructed  and  located,  the  type  of  fan  is  clearly 
shown  in  Fig.  18.  The  base  of  this  wheel  is  a conoidal  iron  casting  with  its 
apex  toward  the  opening  in  the  wall,  so  that  the  air  entering  the  wheel  is 
gradually  deflected  toward  the  numerous  curved  blades  which  extend  outward 
from  the  conoid,  and  are  so  attached 
to  the  back  plate  as  to  make  a 1 
stiff  machine.  A bar  across 
inlet,  and  a trussed  support  on 
the  back,  carry  the  neces- 
sary journal  boxes.  Such  a 
cone  fan  possesses  marked 
advantages  over  a disc  fan 
in  that  it  will  deliver  air 
against  resistance ; back -lash 
is  impossible,  and  the  cen- 
trifugal force  of  the  blades 
is  utilized.  At  a given  pe- 
ripheral speed  the  cone  fan 
will  give  far  superior  results 
in  volume  of  air  moved 
and  in  proportional  power 
expended  Fig.  l6‘  Disc  Wheel- 

Large  numbers  of  these  cone  wheels,  constructed  to  conform  to  propor- 
tions dictated  by  Prof.  S.  H.  Woodbridge,  have  been  furnished  under  specifica- 
tions drawn  by  him  for  prominent  buildings  throughout  the  country. 

When  a sub-basement  is  to  be  kept  tilled  with  air  under  slight  pressure, — 
as  in  the  plenum  system  already  described, — this  fan  is  very  economical  and 
convenient,  as  no  connecting  ducts  are  required,  the  fan  simply  standing  in  the 
sub-basement  and  delivering  directly  into  it.  If  desired,  the  wheel  can  be  fitted 
with  a direct-connected  engine  placed  upon  the  back  side  of  the  wheel ; or,  if 
circumstances  require  it,  the  wheel  may  be  arranged  upon  a vertical  shaft,  with 
step  bearing,  and  driven  by  belt. 


VENTILATION  and  HEATING 


nsHFWm 

) \ -.J.  

^ j 

Mfe  fc>  <g) 

ps*s*  "** 

Fig.  17.  Disc  Wheel, 


WITH  HORIZONTAL  ENGINE. 


72 


W VENTILATION  and  HEATING  « 


Fig.  18.  Cone  Wheel. 


73 


VENTILATION  and  HEATING 


MONOGRAM  EXHAUSTER.  The  most  substantial  form  of  enclosed 
exhaust  fan  is  shown  in  Fig.  19-  The  shell  is  entirely  of  cast  iron,  the  support- 
ing hanger  for  the  journal  boxes  being  bolted  thereto.  Both  bearings,  which 
are  of  exceptional  length  and  arranged  for  thorough  oiling,  are  placed  upon  one 
side  of  the  fan,  leaving  the  inlet  upon  the  other  side  entirely  unobstructed  for 
the  entrance  of  air.  It  is  this  feature  that  distinguishes  an  exhauster  from  a 
blower,  for  the  latter  usually  has  a bearing  upon  each  side  and 

always  has  two  inlet  open-  ings,  one  llPon  either  side, 


while  an  exhauster  has 
that  upon  the  side  oppo- 
An  exhauster  obvi- 
tunity  for  the  ready 
let  to  a system  of  pip- 
sary  feature  in  a venti- 
“ Monogram  ” fans,  so- 
monogram  cast  upon 
larly  built 
zontal  dis- 
in  the  cut. 
structed  to 
zontally  at 
ly  upward 
ward  when 
Fans 
right  or 
ing  as  the 

motor  is  upon  the  right  or  left-hand  side  as  one  faces  the  outlet.  The  illustra- 
tion shows  a right-hand  bottom  horizontal  exhauster.  The  various  discharges 
and  hands  of  fans  are  indicated  upon  succeeding  pages,  showing  outlines  of 
steel  plate  steam  fans. 

The  capacity  of  the  “ Monogram  ” fans  is  relatively  small,  even  in  the  larger 
sizes,  when  compared  with  the  capacity  of  some  of  the  large  steel  plate  fans. 
The  former  type  is,  however,  extremely  serviceable  for  the  ventilation  of  small 
apartments,  or  for  forcing  or  drawing  air  through  long  and  comparatively  small 
conduits  where  the  resistance  to  be  overcome  enters  as  an  important  element. 
Under  these  circumstances  the  particular  value  of  this  fan  lies  in  the  character 
of  its  design,  tor  it  may  be  run  continuously  and  noiselessly  at  the  high  speed 
necessary  to  produce  the  requisite  pressure. 


Monogram”  Exhauster. 


only  a single  inlet,  and 
site  to  the  pulley, 
ously  provides  oppor- 
connection  of  its  in- 
ing,  a very  neces- 
lating  plant.  The 
called  from  the 
the  side,  are  regu- 
with  bottom  hori- 
charge,  as  shown 
They  can  be  con- 
discharge  hori- 
the  top, — direct- 
or directly  down- 
occasion  demands, 
are  designated  as 
left-hand  accord- 
pulley,  engine  or 


74 


m VENTILATION  and  HEAT! 


STEEL  PLATE  PULLEY  LAN.  Lor  the  general  purposes  of  mechanic;! 
ventilation  the  steel  plate  cased  fan  is  now  almost  universally  employed.  The 
pulley  fan,  as  constructed  in  the  smaller  sizes,  is  of  the  form  shown  in  Fig.  20. 
The  sides  and  rim  are  of  steel  plate,  built  up  on  a cast-iron  base  and  provided 
with  a round  outlet  casting.  The  shaft,  pulley  and  fan  wheel  are  all  supported 
by  an  independent  “hanger”  which  is  attached  to  the  side  of  the  fan,  but 
also  rigidly  bolted  to  the  floor 
when  in  position.  The 
wheel  is  thus  overhung 
on  the  shaft,  and  the 
inlet  left  free  for  the 
passage  of  air. 

In  the  larger 
sizes  the  construction 
shown  in  Fig.  21  is 
adopted.  The  sides 
are  braced  by  angle 
iron,  and  upon  each 
side  is  a supporting 
truss  which  carries  a 
journal  box. 

The  shaft  thus 
projects  entirely 
though  the  fan, 
and  the  pulley 
is  overhung 
upon  one  end. 

In  the  illustra- 
tion a blower 
is  shown,  there 
being  an  inlet 
upon  each  side. 

Closing  the  inlet  upon  the  pulley  side  would  transform  it  into  a right-handed 
exhauster,  and  render  it,  like  Fig.  20,  capable  of  attachment  to  a piping  system. 

The  standard  forms  of  steel  plate  fans  are  well  shown  in  the  succeeding  illus- 
trations of  steam  fans.  It  is  evident,  however,  that  any  arrangement  of  discharge 
is  possible,  and  that  the  material  of  construction  makes  it  a comparatively  simple 
matter  to  conform  to  any  special  design  to  suit  the  most  exacting  conditions. 


Fig.  20. 


Steel  Plate  pulley  Exhauster, 

WITH  OVERHUNG  WHEEL. 


75 


mm VENTILATION  and  HEATING  M 


Fig.  21.  Steel  Plate  Blower, 

WITH  OVERHUNG  PULLEY. 


VENTILATION  and  HEATING  « 


ELECTRIC  FAN.  The  rapidly-increasing  adoption  of  electricity  as  a 
motive  power  renders  possible  the  introduction  of  the  electric  fan  with  every 
assurance  of  success.  Whereas,  heretofore,  it  has  usually  been  necessary  to 
provide  a steam  engine  for  the  propulsion  of  a fan,  it  is  now  a simple  matter  to 
install  a fan  with  either  direct-connected  or  independent  motor. 

For  convenience  and  economy,  the  electric  fan  with  motor  directly  attached 
presents  itself  as  most  desirable.  It  is  thus  rendered  compact  and  portable,  may 


cupies  the  minimum  of  space, 
that  is,  those  service- 
single  apart- 
constructed 
rectly  to 
fan  of  the 
as  indica- 
motor  thus 
part  of  the 
adapted  to 
location, 
greater  capaci- 
quired,  the  steel 
fitted  with  a 
the  manner  of 
Evidently,  as  in 
all  steel  plate 
design  in  the 
shape  and  dis- 
may be  follow - 
motor  remain- 
same.  Such  a 

fan  fulfills  all  the  requirements  for  heating  and  ventilating,  and  may  be  readily 
installed  in  connection  with  a heater,  thus  forming  a steam  hot  blast  apparatus. 

But  the  use  of  such  a fan  is  necessarily  largely  in  locations  where  a move- 
ment of  air  is  desired  at  its  natural  temperature,  that  is,  independent  of  the 
heating  system.  If  the  fan  is  to  be  used  where  steam  of  any  reasonable  pressure 
is  employed  for  heating,  it  must  be  obvious  that  the  simplest  and  most  economi- 
cal arrangement  would  call  for  an  engine  to  drive  the  fan,  for  the  exhaust  steam 
could  all  be  utilized  for  heating  purposes. 

For  use  in  the  form  of  an  exhaust  fan,  as  an  adjunct  to  a plenum  system 


be  located  in  any  position,  and  oc- 
In  the  smaller  sizes 
able  for  the  ventilation  of 
ments — a specially 
motor  is  attached  di- 
the  side  of  an  exhaust 
“Monogram”  type 
ted  in  Fig.  22.  The 
becomes  an 
entire  machine,  to  be 
any  given 
Where 
ty  is  re- 
plate fan  is 
motor  after 
Fig.  23. 
the  case  of 
fans,  any 
m after  of 
charge 


ed,  the  fig.  22. 
i n g the 


Monogram”  Electric  Exhauster. 


77 


VENTILATION  and  HEATING 


of  heating,  the  electric  fan  is,  however,  frequently  of  great  service.  It  may  be 
easily  installed  and  operated  in  an  out-of-the-way  position  as  in  any  other, 
and  can  be  arranged  to  be  started  and  stopped  from  a switchboard  in  a much 
more  convenient  location,  so  that  the  attendant  will  seldom  have  to  visit  the  fan. 


Fig.  23.  Steel  Plate  Electric  Exhauster. 


STEAM  FAN.  It  is  always  desirable  that  the  means  of  propulsion  for  a 
fan  should  be  rendered  as  independent  as  possible  of  any  other  source  of  power ; 
in  other  words,  that  the  motor  adopted  should  be  devoted  solely  to  the  driving 
of  the  fan.  Although  the  electric  motor,  as  already  pointed  out,  is  being  very 


78 


/// 


I VENTILATION  and  HEATING 


generally  introduced,  the  steam  engine  stands  as  the  almost  universal  agent  for 
fan  propulsion,  the  combination  of  fan  and  engine  being  designated  a steam  fan. 
As  constructed  of  steel  plate  in  the  smaller  sizes,  the  shell  and  wheel  are 

identical  with  those  used  for  a pul- 
ley fan.  In  the  place  of  the 
pulley  and  its  hanger,  how- 
ever, there  is  provided  a 
special  type  of  centre  - 
crank  upright  engine, 
with  its  cylinder  above 
the  shaft,  supported 
upon  a substantial 
base  and  carrying 
the  fan  wheel  over- 
hung upon  the  end 
of  its  shaft,  all  as 
illustrated  in  Fig.  24. 
In  the  larger  sizes  of 
full  housing  steam 
fans,  the  engine  is  of 
an  entirely  different 
form,  as  shown  in 
Fig.  25,  having  its 
cylinder  beneath  the 
shaft,  the  opposite 
end  of  which  is  sup- 
ported by  a box  in 
the  inlet  of  the  fan. 
Both  types  of  en- 
gines are  particularly 
designed  for  this 
work,  are  of  a high 
grade  of  workmanship,  and  are  capable  of  sustained  operation  at  high  speed. 

Where  exceptional  durability  or  steadiness  in  running  is  desired,  or  where 
it  is  necessary  to  drive  the  fan  above  the  ordinary  speed,  the  type  of  steam  fan 
shown  in  Fig.  26  is  very  efficient,  the  engine  being  double-cylindered  and  of  the 
very  highest  grade.  The  outline  cuts,  Figs.  27  to  34,  are  self-explanatory  of 
the  standard  forms  in  which  all  steel  plate  fans  are  constructed. 


Fig.  24.  Steel  Plate  Steam  Fan. 


79 


VENTILATION  and  HEATING 


Fig.  25.  Steel  Plate  Steam  Fan. 

STANDARD  TYPE. 


80 


VENTILATION  and  HEATING  d 


Fig.  26.  Special  Steel  Plate  Steam  Fan, 


WITH  DOUBLE  ENCLOSED  ENGINE 


VENTILATION  and  HEATING  « 


Fig.  27.  Bottom  Horizontal 
Discharge,  Right  hand. 


Fig.  28.  Up  Blast  Discharge, 
Right  Hand. 


Fig.  29.  Down  Blast  Discharge, 
Left  Hand. 


Fig.  30.  Top  Horizontal  Dis- 
charge, Left  Hand. 


Full  Housing  Steel  Plate  Steam  Fans. 


82 


VENTILATION  and  HEATING 


Fig.  31.  Top  Angular  Down 
Discharge,  Right  Hand. 


Fig.  33.  Bottom  Angular  Down 
Discharge,  Left  Hand. 


Fig.  32.  Bottom  Angular  Up 
Discharge,  Right  Hand. 


charge,  Left  Hand. 


Full  FIousing  Steel  Plate  Steam  Fans. 


83 


VENTILATION  and  HEATING 


Fig.  3S.  Steel  Plate  Pulley  Fan, 

WITH  THREE-QUARTER  HOUSING. 


84 


Mb' VENTILATION  and  HEATING  « 

THREE-QUARTER  HOUSING  FAN.  In  the  case  of  large,  full  housing 
fans,  their  height  frequently  becomes  a serious  obstacle  to  their  introduction. 
As  a means  of  overcoming  this  difficulty,  fans  are,  therefore,  constructed  so 
that  the  lower  portion  of  their  scroll  is  formed  of  brick,  which,  with  its  side 
walls,  serves  at  the  same  time  as  a substantial  foundation.  The  general  idea 
of  such  construction  in  the  case  of  a top  horizontal  three-quarter  housing  pulley 
fan  is  presented  in  Fig.  35.  Here  the  bottom  part  of  the  space  within  the 
enclosing  walls  of  the  foundation  is  cemented  over  to  correspond  to  the  curve 
which  this  portion  of  the  fan  scroll  would  naturally  take  if  the  entire  structure 
were  of  steel  plate. 

The  three-quarter  housing  is  of  especial  advantage  where  it  is  desired  to 
connect  with  an  underground  duct  through  which  the  air  is  to  be  forced.  The 
fan  then  sets  directly  over  the  end  of  the  duct,  as  in  Fig.  36.  The  duct  at  its 
end  conforms  to  a continuance  of  the  curve  at  the  back  of  the  fan.  The  cut 
shows  a steam  fan  in  which,  as  is  customary,  the  engine  is  of  the  horizontal 
type.  The  long  cast-iron  base  of  this  engine,  attached  to  the  substantial  brick 
foundation,  furnishes  an  exceptionally  solid  support,  and  renders  the  entire  con- 
struction perfectly  rigid.  The  engine  proper  is  identical  in  construction  with 
the  regular  independent  engines  of  the  same  form,  is  provided  with  adjustment 
for  all  moving  parts,  is  completely  equipped  with  oiling  devices,  and  thoroughly 
built  for  continuous  operation. 

The  utility  of  such  a design  must  be  evident ; in  fact,  this  is  the  accepted 
form  for  introduction  in  the  case  of  almost  all  plants  of  large  size.  The  under- 
ground brick  duct  permits  of  the  distribution  of  air  to  the  vertical  tines  without 
encroaching  on  valuable  tloor  space  or  head  room. 

The  three-quarter  housing  fans  are  constructed  in  the  same  standard  forms 
of  discharge  as  are  the  full  housing  fans  illustrated  in  Figs.  2 7 to  34  inclusive. 
From  this  large  assortment  may  be  readily  chosen  the  shape  that  is  best  suited 
to  the  conditions  under  which  it  must  be  installed.  At  all  events,  a fan  of  this 
type  can  be  specially  constructed  to  meet  almost  any  conceivable  requirements. 

The  duplex  type  of  three-quarter  housing  steam  fan,  illustrated  in  connec- 
tion with  a heater  upon  a succeeding  page,  is  frequently  of  great  convenience. 
Each  fan  is  provided  with  its  individual  engine,  and  the  fans  set  side  by  side 
with  their  shafts  in  the  same  line.  The  shafts,  which  are  extended  until  they 
meet,  are  rigidly  connected  by  a coupling.  Under  ordinary  conditions  both 
engines  are  operated ; but,  if  under  any  circumstances,  one  of  these  becomes 
disabled,  they  may  both  be  driven  at  only  twenty  per  cent,  less  speed  by  the 
other  engine. 


85 


M VENTILATION  and  HEAT1NGM 


86 


Fig.  36.  Steel  Plate  Steam  Fan, 

WITH  THREE-QUARTER  HOUSING. 


VENTILATION  and  HEATING 


SINGLE  UPRIGHT  ENGINE.  The  most 
mechanical  heating  and  ventilating  plant  is 
tor.  It  is,  therefore,  essential  above  all  else 
and  construction  should  be  as  near  perfection 
The  engine  being  the  most  generally  employed 
propulsion,  has  received,  at  the  hands  of  this 
most  careful  attention.  For  general  indepen- 
well  as  for  the  driving  of  fans  by  belt,  these 
built  in  a variety  of  forms,  each  best  suited  to 
The  single-cylindered  up- 
shown  in  Fig  37  is  provided 
tling  governor.  The  entire 
pie,  strong  and  pleasing  in 
The  valve  is  of  the  bal- 
and  receives  its  motion  direct- 
trie  upon  the  shaft.  The  wheel, 
ly  heavy,  is  designed  for  a 
but  may  be  utilized  as  a band 
site  end  of  the  shaft  is  splined 
ditional  wheel 
The  cylin- 
lagged.  The 
from  a station- 
oiler,  and  all 
cept  that  no  the 
stationary  and 
by  dropping 
Although 
g i n e s are 
constructed 
pressure, 
alsofurnish- 
line  of  sizes 
cyl  inders 
be  operated 
of  40  lbs. 


delicate 


Fig.  37. 


mechanism  in  any 
usually  the  mo- 
that  its  design 
as  possible, 
means  of  fan 
Company,  the 
dent  work,  as 
engines  are 
its  given  duty, 
right  engine 
with  a throt- 
frame  is  sim 
outline. 

anced-pi-ston  type 
ly  from  the  eccen- 
which  is  exceeding- 
balance  wheel, 
wheel.  The  oppo- 
to  receive  an  ad- 
if  it  be  necessary, 
der  is  thoroughly 
crank  pin  is  oiled 
ary  sight-feed 
other  oil  cups,  ex- 
cross-head, are 
feed  moving  parts 
the  oil  into  cups, 
these  en- 
regularly 
for  high 
they  are 
ed  in  a full 
with  large 
designed  to 
at  pressures 
and  under, 


Single  Upright  Engine. 
which  are  usually  prevalent  in  heating  plants.  A small  engine  of  great  power 
can  thus  be  furnished  at  a comparatively  low  price. 


87 


VENTILATION  and  HEATING 


DOUBLE  UPRIGHT  ENCLOSED  ENGINE.  Where  perfection  in 
operation,  the  possibility  of  high  speed  without  noise,  or  the  complete  exclusion 
of  dust  from  the  running  parts,  is  desired,  the  type  of  engine  represented  in 

Fig.  38  may  be  adopted.  The  cylinders 
are  placed  side  by  side  in  the  same  casting; 
the  cranks  are  set  opposite ; the  recipro- 
cating parts  are  balanced  in  their  move- 
ments and  high  speed  is  made  possible. 
The  cylinders  are  of  large  diameter  as 
compared  with  the  stroke,  so  that  great 
power  may  be  developed  at  high  rotative 
but  moderate  piston  speed. 

The  steam  admission  to  both  cylinders 
is  regulated  by  a single  piston  valve,  under 
the  control  of  a shaft  governor  of  the 
same  design  as  that  used  upon  the  single 
upright  engines.  All  moving  parts  sub- 
ject to  friction  are  of  steel  and  the  bearings 
of  ample  size.  Automatic  re- 
lief valves  are  provided  to 
prevent  any  danger  of 
damage  by  water  in  the 
cylinder.  Complete 
sight-feed  oiling  ar- 
rangements from  a sin- 
gle oil  tank  connect 
with  all  of  the  bearings 
and  the  frame  is  so 
constructed  as  to  en- 
tirely enclose  all  run- 
ning parts,  while  still 
leaving  them  accessible 
by  merely  opening  the 
door.  A throttling  gov- 
ernor is  usually  em- 
ployed when  the  engine 
is  used  in  connection 
with  a heating  plant. 


Fig.  38.  Double  Upright  Enclosed  Engine. 


88 


VENTILATION  and  HEATING 


HORIZONTAL  ENGINE.  The  form  of  centre-crank  horizontal  engine 
illustrated  in  Fig.  39,  is  of  a type  largely  used  in  connection  with  heating-plants. 
It  is  here  shown  with  a throttling  governor,  but  is  otherwise  identical  with  the 
regular  Sturtevant  automatic  engine  of  this  type. 

The  valve,  which  is  of  the  balanced-piston  type,  is  provided  with  snap  rings 
and  operates  in  a removable  bushing,  thereby  making  it  a simple  matter  to 
always  keep  it  tight.  Motion  is  transmitted  to  this  valve  through  an  adjustable 
slide  connec-  tion  upon  the  side  of  the  frame.  Continuous  sight- 


Fig.  39.  Low  Pressure  Horizontal  Engine. 

The  frame  with  the  attached  oil  guard  and  removable  side  plates  practically 
enclose  the  running  parts  of  the  engine,  preventing  the  throwing  of  oil  and 
largely  decreasing  the  annoyance  from  dust  and  grit.  A substantial  bed  plate 
forms  a part  of  the  complete  engine. 

Each  size  high-pressure  engine  frame  of  this  type  is  fitted  with  cylinders  of 
two  diameters,  both  having  the  same  stroke.  The  smaller  diameter  is  designed 
for  a maximum  of  150  pounds,  and  the  larger  for  100  pounds.  Special  sizes, 
with  extra  large  cylinders  and  balanced  slide  valves,  are  also  constructed  for  use 
at  low  pressure,  and  are  thus  rendered  available  for  a special  line  of  work  for 
which  few  engines  are  distinctly  constructed ; in  fact,  the  Sturtevant  low  pressure 
engines  stand  practically  alone  in  their  class. 


89 


VENTILATION  and  HEATING 


HEATERS. 

CORRUGATED  SECTIONAL  BASE  HEATER.  The  heater  itself  must 
be  compact,  efficient,  easily  operated  or  repaired,  and  of  such  construction  as 
to  make  a change  in  its  capacity  a simple  matter.  All  of  these  features  were 
carefully  considered  in  the  design  of  the  Sturtevant  Heater,  and  the  proportions 
in  which  the  individual  heaters  are  made  up  for  use  are  regulated  by  formulas 
derived  from  the  extensive  experiments  previously  related. 

In  Fig.  40,  is  indicated  in  detail  the  general  construction  of  the  indi- 
vidual sections  of  a heater. 

The  foundation  upon  which 
the  heater  rests  is  constructed 
entirely  of  steel  angles, flanged 
and  bolted.  Upon  this,  and 
the  expansion  balls,  rests  a 
series  of  sectional  bases,  each 
section  containing  either  two 
or  four  rows  of  vertical  pipes, 
accordingtothe  requirements, 
connected  by  cross  pipes  at 
the  top  as  shown.  The  length 
of  these  pipes  and  their  posi- 
tion prevents  the  evil  effects  J 
of  the  unequal  expansion  of  J 
the  pairs  of  vertical 
pipes,  which  in  heat- 
ers of  other  makes, 
frequently  have  return 
bends  in  place  of  cross 
pipes.  Free  expan- 
sion lengthwise  of  the 
sections  is  allowed  for 
by  resting  one  end  of 
the  sections  upon 
balls,  E,  Fig.  41,  which 
are  supported  by  a casting  beneath. 

In  order  to  prevent  alternate  expansion  and  contraction  of  the  air  between 
the  pipes  in  the  heater,  and  at  the  same  time  economize  room  and  material,  the 


Fig.  40.  CORRUGATED  SECTIONAL  BASE  HEATER. 


90 


m VENTILATION  and  HEATING 


sides  of  the  sections  are  corrugated  so  that  they  tit  each  other  closely  and  allow 
an  equidistant  spacing  of  the  pipes  in  the  heater.  Upon  the  end  of  each  section 
is  a circular  flanged  head,  divided  by  a horizontal  diaphragm,  the  upper  part  com- 
municating with  the  steam  supply,  and  the  lower  with  the  drip.  The  sides  of  the 
heads  are  surfaced  and  closely  fitted  ; a blank  flange  is  placed  at  one  end  of  the 
series  and  the  large  steam  inlet  and  drip  header  at  the  other.  These  heads  are 
tightly  drawn  together  by  substantial  through  bolts,  and  tight  joints  are  posi- 
tively secured  by  the  use  of  special  gaskets.  The  upper  parts  of  all  sections 
thus  communicate  with  the  inlet  and  the  lower  parts  with  the  drip. 

Steam  is  admitted  through  the  inlet  pipe  A,  passes  into  the  sections,  thence 


up,  over  and 
in  the  see- 
the drip, 
er  as  water, 
through  the 
Every 
inch  of 
ing  sur- 
pipes  and 
thus  util- 
water  is 


down 


pipes,  into  the  separate  space 
tion,  which  communicates  with 
whence  it  leaves  the  heat- 
of  condensation, 
drip  pipe  B. 
square 


Fig.  41. 
Corrugated 
Sectional 
Base  Heater. 


; the  heat- 
face  of  the 
section  is 
ized,  and  the 
conveyed  away  through 
the  pipe  in  the  header,  in  the  upper  part  of  which  steam  is  admitted.  A small 
hole  in  the  horizontal  diaphragm,  near  the  middle  of  the  section,  allows  of  com- 
plete drainage  of  the  water  from  each  section. 

The  pipes,  C and  D,  are  respectively  the  exhaust  steam  inlet  and  drip  for 
the  single  independent  section  provided  to  utilize  the  exhaust  steam  from  the 
fan  engine.  This  section  is  made  without  a head  and  is  not  in  communication 
with  the  other  sections. 

The  areas  for  the  inlet  and  drip  are  very  large  and  direct,  giving  an  oppor- 
tunity for  the  use  of  exhaust  steam  without  back  pressure  upon  the  engine. 
This  arrangement  does  away  with  all  inlet  pipes  and  manifolds,  with  their 
numerous  flanges  and  bolts ; there  are  no  connecting  nipples,  allowing  of  con- 
stant racking  by  unequal  expansion,  and  above  all,  the  inlet  and  drip  are  both  at 
the  same  end  of  the  section,  avoiding  the  great  disadvantage  of  connecting  at 
the  opposite  ends  of  the  section.  When  desired,  the  sections  may  be  made  up 
in  more  than  one  group,  so  as  to  use  exhaust  steam  in  one  portion  and  live  in 
the  other.  Every  heater  is  encased  in  a steel  plate  jacket,  preventing  all  possi- 
bility of  tire,  and  allowing  of  the  securing  of  lower  insurance  rates. 


91 


VENTILATION  and  HEATING 


STEAM  TRAP.  The  Sturtevant  steam  trap  is  especially  designed  for  use 
in  connection  with  the  Sturtevant  heaters,  although  it  is  equally  well  fitted  to 
remove  the  water  of  condensation  from  steam  heaters  or  radiators  of  any  con- 
struction. Its  action  will  be  made  clear  by  Figs.  42  and  4).  As  seen  in  the 
sectional  view,  the  body  of  the  trap  contains  a pot,  which,  as  the  water  flows 
from  the  inlet  upon  the  left  into  the  space  around  the  pot,  rises  and  closes  the 
connection  between  the  interior  and  exterior.  The  water  accumulates  in  this 
space  and  gradually  overflows  into  the  pot  until  its  buoyancy  is  overcome  and  it 
sinks  to  the  bottom. 

By  this  accumulative  action  free  passage  for  the  water  is  afforded  from  the 
pot  up  through  the  vertical  hollow  extension  of  the  cover  and  thence  through 
the  cored  passage  in  the  cover  to  the  outer  air.  The  pressure  of  the  steam  upon 
the  surface  of  the  water  causes  this  discharge  to  be  rapid,  and  it  continues  until 
the  levity  of  the  pot  becomes  sufficient  to  cause  it  to  rise  and  prevent  the  passage 
of  water  by  the  seating  of  the  extension  against  the  cone  screwed  into  the  bot- 
tom of  the  pot.  Both  extension  and  cone  are  of  brass,  and  are  ground  to  a 
tit,  ensuring  a tight  joint  when  in  contact. 


Fig.  42.  Steam  Trap.  Fig.  43. 


The  periodic  delivery  of  water  continues  as  long  as  there  is  water  to  dis- 
charge or  sufficient  steam  pressure  to  cause  the  trap  to  act.  These  traps  are 
specially  constructed  to  act  at  different  steam  pressures. 

Although  certain  types  of  steam  traps  are  designed  to  return  the  water  of 
condensation  to  the  boiler,  the  Sturtevant  trap  is  not  intended  for  this  service, 
but  merely  to  permit  of  the  removal  of  water  from  the  heater  without  the 
escape  of  steam. 


92 


VENTILATION  and  HEATING 


AUTOMATIC  RETURN  WATER  APPARATUS.  Economy  demands 
that  in  any  heating  plant  the  water  of  condensation  from  the  steam  should  be 
returned  to  the  boiler.  With  a simple  gravity  system  or  with  a hot  blast  appa- 
ratus placed  sufficiently  above  the  water  level  of  the  boilers,  the  matter  of  return 
of  water  is  simple.  But  the  ordinary  plant  for  the  Blower  System  is  placed 
upon  the  floor,  generally  well  below  the  level  of  the  boilers.  Some  positive  and 
additional  means  is  therefore  necessary  to  lift  the  water  and  force  it  into  the 
boiler  against  the  existing  steam  pressure. 

For  this  purpose  in  plants  of  any  reasonable  size  a steam  pump  is  employed. 
The  water  escaping  from  the  heater  is  first  discharged  into  a tank,  which  is 


with  a float  valve,  by  the  ac- 
steam  is  admitted  to  the  pump 
water  reach- 
level  within 
The  pump 
motion  op- 
the  water 
reduced  to 
that  the  float 
but  this  time 
steam  a d- 
the  pump, 
al  form  of 
nation  of 
receiver  is 

shown  in  Fig.  44.  The  latter  is  so  placed  with  relation  to  the  pump  as  to  permit 
of  the  natural  flow  of  water  thereto.  A gauge  glass  on  the  end  of  the  receiver 
indicates  the  water  level  within.  The  pump  is  of  the  duplex  pattern,  always  to 
be  chosen  for  this  class  of  work  as  it  ensures  more  steady  running  and  is  far  less 
liable  to  stoppage  than  a single-piston  pump. 

When  water  of  condensation  is  to  be  discharged  into  the  receiver  from 
several  sources,  as  from  direct  radiators  in  the  building  and  from  a regular  hot 
blast  heater  at  the  same  time,  it  is  necessary  that  traps  be  interposed,  otherwise 
unequal  condensation  in  different  groups  or  coils  will  tend  to  a backing  up  of 
water  in  those  in  which  the  condensation  is  most  rapid,  and  hence  the  pressure 
is  least.  With  exhaust  steam  discharged  directly  into  the  receiver  a trap  is 
positively  necessary  in  the  connections  from  other  coils  using  live  steam  and 
discharging  into  the  same  receiver. 


provided 
tion  of  which 
when  the 
es  a certain 
the  tank, 
thus  set  in 
crates  until 
has  been 
such  a level 
again  acts, 
closes  t h e 
mission  to 
The  usu- 
the  combi- 
pump  and 


Fig.  44.  Automatic  Return 
Water  Apparatus. 


93 


94 


Fig.  4?.  Combined  Cone  Fan  and  Heater. 


VENTILATION  and  HEATING 

HEATING  AND  VENTILATING  APPARATUS. 

COMBINED  CONE  FAN  AND  HEATER.  The  simplest  apparatus  con- 
sists of  a cone  fan  enclosed  within  the  heater  case,  as  shown  in  Fig.  45.  By  the 
fan’s  action  air  is  forced  between  the  pipes  of  the  heater.  The  opposite  end  of 
the  heater  may  be  left  open  or  connected  by  a suitable  duct  with  any  given  apart- 
ment. For  such  apparatus  the  cone  fan  is  far  more  efficient  and  desirable 
than  the  disc  or  propeller  fan,  because  of  its  more 
positive  operation  against  resistance. 

MONOGRAM  EXHAUSTER 
AND  SOLID  BASE  HEATER.  In 
the  smallest  sizes  of  heating  and  venti- 
lating apparatus  in  which  a cased  fan  is 
used  in  connection  with  a heater,  the 
arrangement  is  as  indicated  in  Fig.  46. 

The  “ Monogram  ” fan  has  already  been 
described.  The  type  of  heater  here 
illustrated  is  known  as  the  “ Solid  Base 
Heater,”  and  is  distinguishable  from  the 
corrugated  sectional  base  heaters  used 
in  connection  with  the  steel 
plate  fans  by  the  fact  that 
only  a single  casting  is 
used  for  each  entire 
heater.  The  steam  sup- 
ply pipe  for  these 
heaters  enters  the 
base  at  the  bottom 
on  one  side,  and  the 
water  of  condensa- 
tion escapes  from  the 
bottom  on  the  op- 
posite side.  A dia- 
phragm in  the  base 
compels  the  steam 

to  flow  through  all  fig.  46.  monogram  Exhauster  and  Solid 
the  pipes,  thus  util-  Base  heater. 


95 


VENTILATION  and  HEATING 


96 


Fig.  47.  Steel  Plate  Exhauster, 

WITH  OVERHUNG  WHEEL  AND  CORRUGATED  SECTIONAL  BASE  HEATER. 


VENTILATION  and  HEATING 


izing  all  the  heating  surface.  The  pipes  are  of  steel,  and  the  heater  entirely 
encased  in  steel  plate,  with  a receiving  chamber  for  the  air  where  it  enters  the 
fan.  Ordinarily  the  air  is  taken  in  at  the  top,  either  from  the  room  or  through 
a pipe  connecting  with  the  desired  fresh  air  supply.  The  air  discharged  from 
the  fan  can  be  conveyed  to  any  point  by  means  of  distributing  pipe.  All  these 
heaters  are  designed  to  use  either  live  or  exhaust  steam. 


HEATING  AND  VENTILATING  APPARATUS  WITH  PULLEY  FAN. 
The  ordinary  installation  of  the  Blower  System  requires  an  apparatus  of  larger 
capacity  than  can  be  conveniently  constructed  of  the  type  just  described.  To 
suit  all  requirements,  it  is  necessary  that  the  construction  of  the  heater  should 
be  such  as  to  permit  of  the  most  extended  range  in  its  sizes,  while  the  fan  must 
be  of  a type  in  which  the  largest  capacity  may  be  secured  when  desired. 

In  its  simplest  form,  such  an  apparatus  is  presented  in  Fig.  47.  The  fan  is 
of  the  steel  plate  pattern,  driven  by  belt,  and  constructed  as  already  described. 
In  the  larger  sizes  of  pulley  fans  the  “hanger”  is  omitted,  the  wheel  is  not 
overhung,  and  the  shaft  is  supported  by  a box  on  each  side  of  the  shell,  as  in 
Fig.  21.  The  heater  here  consists  of  four  independent  corrugated  sections  of 
four  rows  of  pipes  each,  of  the  type  shown  in  Figs.  46  and  47.  The  air  passing 
through  the  heater  is,  therefore,  brought  in  contact  with  sixteen  rows  of  pipe. 
As  these  pipes  are  set  staggering,  and  by  means  of  the  corrugations,  the  sections 
are  allowed  to  interlock  each  other,  the  currents  of  air  are  broken  up  completely 
and  the  highest  efficiency  secured.  Obviously,  more  or  less  sections  could  be 
provided,  and  they  could  be  separated  by  a blank  flange  in  such  a manner  as  to 
permit  of  using  live  steam  in  one  of  the  groups  thus  formed  and  exhaust  steam 
in  the  other.  The  lower  pressure  steam  coils  are  always  so  located  as  to  be  first 
presented  for  contact  with  the  air  before  it  passes  across  the  pipes  of  the  higher 
pressure  group,  where  its  temperature  is  increased. 

The  location  of  the  drip  is  clearly  shown.  When  live  steam  is  used  this  is 
connected  with  a steam  trap  provided  for  the  purpose,  in  order  to  free  the  heater 
of  water  without  allowing  any  escape  of  steam. 

Arranged  as  here  shown,  this  is  known  as  a “ draw-through  apparatus,”  the 
air  first  passing  through  the  heater  before  it  enters  the  fan.  The  direction  of 
discharge  of  heated  air  from  the  apparatus  is,  therefore,  entirely  dependent  upon 
the  construction  of  the  fan.  Although  here  shown  with  a bottom  horizontal 
discharge,  it  is  evident,  from  preceding  descriptions,  that  fans  of  this  type  are 
regularly  made  in  a large  variety  of  directions  of  discharge,  so  that  change  in 
direction  of  the  air  after  once  leaving  the  fan  is  usually  avoided. 


97 


VENTILATION  and  HEATING 


Fig.  48.  Standard  Heating  and  Ventilating  Apparatus. 

small  SIZE. 

side  of  the  crank,  leaving  the  fan  inlet  unobstructed.  In  the  apparatus  shown 
in  Fig.  48  the  fan  has  a top  horizontal  discharge. 

The  heater  is  constructed  on  three  sections,  each  having  four  rows  of  pipe, 
all  connecting  with  the  same  inlet  header,  and  one  section  of  two  rows  (not  seen 
in  cut)  provided  to  utilize  the  exhaust  steam  from  the  fan  engine.  Either  live 
or  exhaust  steam  may  be  used  in  the  heater. 

Heaters  of  this  size  are  usually  set  up  on  a timber  frame,  so  as  to  allow 
of  placing  the  trap  upon  the  floor  and  connecting  the  drip  directly  to  it. 


STANDARD  HEATING  AND  VENTILATING  APPARATUS.  As  has 
already  been  indicated,  a steam  engine  is  an  almost  indispensable  requisite  to 
any  steam  hot  blast  apparatus  of  more  than  moderate  size.  For  compactness 
nothing  can  excel  the  combination  of  corrugated  sectional  base  heater  and  steel 
plate  steam  fan.  In  the  smallest  apparatus,  of  which  the 
steam  fan  forms  a part,  the  latter  is  of  the  type  already 
illustrated,  with  vertical  engine,  having  its  cylinder  above 
the  shaft,  and  provided  with  two  bearings,  one  upon  either 


A A A * A 


-* 


98 


VENTILATION  and  HEATING  « 


99 


Fig.  49.  Standard  Heating  and  Ventilating  Apparatus. 


VENTILATION  and  HEATING  d 


In  the  larger  sizes  the  apparatus  maintains  its  general  form,  the  principal 
change  being  in  the  construction  of  the  steam  fan,  which,  as  indicated  in  Fig.  49, 
has  the  engine  cylinder  beneath  the  shaft. 

BLOW-THROUGH  HEATING  AND  VENTILATING  APPARATUS. 
In  the  introduction  and  erection  of  the  Sturtevant  steam  hot  blast  apparatus,  it 
frequently  happens  that  the  space  allotted  is  of  such  a shape  as  to  preclude  all 
possibility  of  placing  an  apparatus  of  the  ordinary  form,  arranged  to  draw  the 
air  through  the  heater  before  it  passes  through  the  fan.  If  the  space  is  narrow, 
but  of  considerable  length,  it  is  often  a very  simple  matter  to  construct  the  fan 
to  blow  the  air  through  -the  heater,  as  illustrated  in  Fig.  50.  This  makes 
a narrow,  but  long,  apparatus  of  equal  efficiency  with  the  regular  standard 
apparatus.  Such  an  arrangement  is  frequently  desirable  where  a pulley  fan  is 
to  be  used  in  place  of  a steam  fan,  and  it  would  be  impossible  to  belt  directly  to 
a fan  arranged  in  the  regular  manner. 

The  outlet  from  the  heater  may  be  placed  in  almost  any  position  at  the  end 
of  the  heater,  so  as  to  discharge  either  directly  outward  at  the  end,  or  upward, 
downward,  to  the  right,  or  to  the  left.  The  discharge  of  the  fan  is  always 
made  such  as  to  cause  the  most  thorough  circulation  of  the  air  passing  through 
the  heater, — that  is,  with  the  discharge  at  the  top  of  the  heater  the  fan  would 
have  a bottom  horizontal  discharge,  while  with  a bottom  discharge  on  the  heater 
the  fan  would  be  top  horizontal,  as  shown  in  the  cut. 

The  heater  shown  in  the  cut  consists  of  four  sections,  each  having  four 
rows  of  pipes,  and  all  being  bolted  together  in  a single  group  connecting  with 
the  same  inlet  header  and  drip.  Either  live  or  exhaust  steam  may  be  used  in 
this  portion  of  the  heater ; in  the  former  case,  the  water  of  condensation  is 
discharged  through  a steam  trap,  while  in  the  latter  it  has  a free  delivery  to 
the  open  air,  or  connects  with  a return  system.  In  addition  to  these  sections 
is  one  more,  to  utilize  the  exhaust  steam  from  the  fan  engine.  This  section, 
having  no  circular  head  and  not  projecting  through  the  heater  casing,  cannot 
be  seen. 

The  section  into  which  is  discharged  the  fan  engine  exhaust  is  always  so 
placed  in  the  heater  as  to  be  the  first  with  which  the  cold  air  comes  in  contact, 
because  exhaust  steam,  having  a lower  temperature  than  live  steam,  would  have 
but  little  effect  in  heating  air  which  had  already  passed  through  the  live  steam 
coil.  It  is  customary  in  heating  and  ventilating  plants  employed  in  manufactur- 
ing establishments  to  use  in  the  main  group  the  exhaust  from  the  mill  or  shop 
engine  during  the  day,  and  live  steam  during  the  night. 


100 


VENTILATION  and  HEATING 


iOI 


Fig.  $0.  Heating  and  Ventilating  Apparatus, 

ARRANGED  TO  BLOW  THROUGH  HEATER. 


M VENTILATION  and  HEATING  @@ 


102 


Fig.  Si.  Standard  Heating  and  Ventilating  Apparatus, 

WITH  THREE-QUARTER  HOUSING  STEAM  FAN. 


VENTILATION  and  HEATING 


STANDARD  HEATING  AND  VENTILATING  APPARATUS,  WITH 
THREE-QUARTER  HOUSING  FAN.  The  three-quarter  housing  fans,  in 
various  types,  have  already  been  described.  In  combination  with  heaters  they 
form  a class  of  apparatus  almost  universally  adopted  where  a plant  of  any 
reasonable  size  is  to  be  installed  in  a basement.  Such  an  apparatus,  consisting  of 
a three-quarter  housing  top  horizontal  discharge  steam  fan  and  sectional  base 
heater,  is  illustrated  in  Fig.  51. 

The  inlet  connection,  which  is  shown  between  the  fan  and  heater,  is  com- 
paratively low,  and  practically  forbids  the  use  of  a heater  section  much  greater 
than  its  own  height.  The  alternative,  in  order  to  provide  a sufficiently  large 
heater,  is  to  build  it  in  two  groups,  placed  end  to  end  and  parallel  to  the  side  of 
the  fan.  Such  an  arrangement  is  adopted  in  the  apparatus  illustrated,  although 
the  heads  of  only  one  group  can  be  seen.  The  group  shown  is  provided  with  a 
large  inlet  and  drip  header,  with  connections  for  the  use  of  exhaust  steam. 

The  utility  of  an  apparatus  of  this  description  must  be  evident  where  the 
heated  air  is  to  be  conducted  through  pipes  suspended  beneath  the  ceiling.  The 
height  of  the  fan  outlet  is  such  as  to  make  the  discharge  direct  without  change 
of  direction. 


BLOW-THROUGH  HEATING  AND  VENTILATING  APPARATUS, 
WITH  THREE-QUARTER  HOUSING  PULLEY  FAN.  It  must  be  obvious 
that  a pulley  fan  may  be  as  readily  employed  as  a steam  fan  in  connection  with 
a heater.  The  former  arrangement  is  represented  in  Fig.  52,  but  the  heater  is 
so  located  that  the  air  is  blown,  rather  than  drawn,  through  it,  the  fan  having  an 
extra  large  outlet.  Under  such  circumstances  a blower  can  be  as  well  used  as 
an  exhauster,  and,  where  the  air  is  to  be  taken  from  the  apartment  in  which  it 
stands,  is  much  to  be  preferred. 

The  extreme  length  of  a double  group  of  ordinary  sections  placed  end  to 
end,  and  having  sufficient  heating  surface,  precludes  such  arrangement  for  a 
blow-through  apparatus,  because  of  the  inability  of  the  fan  to  distribute  the 
air  equably  over  the  entire  heating  surface.  But  greater  height  is  seldom 
objectionable,  so  that  ample  heating  surface  can  usually  be  arranged  in  this 
manner. 

As  represented,  this  apparatus  is  fitted  and  flanged  to  utilize  exhaust  steam 
in  two  sections  nearest  the  fan,  while  the  remaining  sections,  separated  from  the 
former  by  a blank  flange,  are  designed  to  be  supplied  with  live  steam.  Evi- 
dently this  type  of  apparatus  possesses  the  same  advantages  as  to  adaptability 
to  certain  spaces  as  does  the  same  arrangement  with  a full  housing  fan. 


103 


wBm 


m VENTILATION  and  HEATINGM 


104 


Fig.  52.  FIeating  and  Ventilating  Apparatus, 

ARRANGED  TO  BLOW  THROUGH,  WITH  THREE-QUARTER  HOUSING  PULLEY  FAN 


VENTILATION  and  HEATING 


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VENTILATION  and  HEATING 


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Fig.  54.  Heating  and  Ventilating  Apparatus, 

FOR  HOT  AND  COLD  SYSTEM. 


VENTILATION  and  HEATING  « 


DUPLEX  HEATING  AND  VENTILATING  APPARATUS,  WITH 
THREE-PULLEY  RIG.  The  advantages  of  a duplex  fan  have  already  been 
pointed  out,  in  that  greater  capacity  can  be  secured  within  a given  height,  and 
the  danger  of  inconvenience  from  accident  is  less. 

Several  arrangements  of  the  heater  are  possible  with  the  duplex  fan,  the 
most  common  being  that  shown  in  Fig.  53-  The  fans  are  built  as  exhausters, 
each  with  only  a single  inlet,  and  that  on  the  side  opposite  the  engine.  These 
two  inlet  sides  face  each  other,  so  that  the  entire  space  between  the  fans  and 
connecting  with  these  inlets  can  be  readily  enclosed  and  connected  with  the 
heater,  which  is  usually  symmetrically  arranged  and  placed  immediately  behind 
the  fans.  The  heater  shown  in  the  cut  is  constructed  in  three  groups,  forming 
three  sides  of  a square,  and  offering  a large  area  for  the  admission  of  air  to  the 
fans;  only  the  open  end  of  one  group  is  clearly  represented.  The  sections 
being  arranged  symmetrically,  a uniform  velocity  of  the  entering  air  is  secured 
through  all  parts  of  the  heater. 

This  type  of  apparatus,  when  introduced  for  mill  heating,  is  generally 
placed  midway  of  the  length  of  the  mill,  and  discharges  the  heated  air  into  a 
continuous  brick  duct  extending  along  the  wall  on  one  side  of  the  mill.  The 
ducts  from  the  two  fans  join  before  entering  this  main  duct,  and  are  provided  at 
their  junction  with  a gate  which  automatically  regulates  the  discharge  of  air  from 
the  fans,  and  completely  closes  the  outlet  of  either  fan  if  it  is  stopped. 

In  textile  and  similar  mill  heating  the  heaters  are  designed  to  use,  during 
the  day,  either  exhaust  steam  from  the  mill  engine,  if  it  is  non-condensing,  or 
low  pressure  steam  from  the  intermediate  receiver,  if  the  engine  is  condensing. 
The  exhaust  steam  from  the  fan  engines  themselves  is  often  sufficient  to  keep 
the  mill  comfortable  during  the  night. 

Pulley  fans  can  be  readily  employed,  and  a special  arrangement  of  tight 
and  loose  pulleys  introduced,  so  as  to  allow  of  driving  the  fans  by  belt  from  the 
main  line  during  the  day,  and  by  belt  from  a small  independent  engine  during 
the  night.  This  is  the  arrangement  illustrated  in  Fig.  53.  The  engine  is  of 
the  regular  horizontal  type,  and  is  provided  with  an  extra  heavy  fly  wheel,  with 
face  of  double  width,  to  permit  of  the  shifting  of  the  belt. 

The  middle  pulley  upon  the  fan  is  rigidly  keyed  to  the  fan  shaft.  The 
other  two  pulleys,  one  on  either  side,  are  carried  upon  sleeves  extending  from 
the  ends  of  the  adjacent  boxes.  When  the  fan  is  to  be  driven  by  the  engine, 
the  belt  from  the  latter  is  shifted  on  to  the  middle  pulley,  while  that  from  the 
line  shaft,  which  is  usually  standing  still  during  the  operation  of  the  fan  engine, 
is  left  idle  upon  the  pulley  nearest  the  fan. 


107 


M VENTILATION  and  HEATING  M 

HEATING  AND  VENTILATING  APPARATUS  FOR  HOT  AND 
COLD  SYSTEM.  It  is  evident  that  if  an  apparatus  is  to  be  employed  to  dis- 
charge either  hot  or  cold  air  at  will,  the  fan  must  be  so  located  that  it  can  force 
the  air  (not  draw  it)  through  the  heater  or  by-pass  around  it.  This  arrange- 
ment, of  the  type  very  generally  employed  in  schoolhouse  and  public  building 
work,  is  represented  in  Fig'.  54. 

The  fan  is  a blower  constructed  with  extra  large  outlet,  so  as  to  secure  the 
most  thorough  distribution  of  the  air  across  the  pipes  of  the  heater.  Above  the 
heater  pipes  is  provided  a by-pass,  in  which  is  introduced  a damper  which  may 
be  closed  to  the  passage  of  cold  air,  if  desired.  Two  separate  pipes  conduct  the 
air  of  the  different  temperatures  away  from  the  heater.  The  sections  are  made 
up  in  two  groups,  each  arranged  for  separate  steam  supply  and  drip.  When 
the  distributing  ducts  are  to  be  underground,  or  when  it  is  desired  to  have  the 
by-pass  under  the  heater,  the  fan  can  be  constructed  with  a bottom  horizontal 
discharge,  and  the  heater  sufficiently  raised,  if  necessary,  to  allow  the  air  to 
by-pass  beneath  it. 

The  engine  is  of  the  low  pressure  horizontal  type,  controlled  by  throttling 
governor  and  arranged  to  drive  the  fan  by  belt.  If  desired,  the  engine  could 
have  been  located  beside  the  heater  in  such  a way  as  to  drive  the  apparatus  from 
that  end,  and  thus  somewhat  reduce  the  length  of  the  plant. 

Various  other  types  of  fans,  engines,  heating  and  ventilating  apparatus, 
together  with  dimensions  and  capacity  tables,  are  presented  at  length  in  the 
regular  trade  catalogues  published  by  this  Company. 


108 


APPLICATION 


OF  THE 


STURTEVANT  SYSTEM  OF  HEATING  AND 

VENTILATION. 


HE  following  illustrations  and  descriptions  are  introduced  here  simply  as 


1 characteristic  types  of  the  application  of  the  Sturtevant  System  of  Heat- 
ing and  Ventilation,  and  as  the  most  fitting  testimonials  to  the  efficiency  of  the 
system  and  apparatus  introduced  by  this  house*.  As  has  already  been  made 
evident,  no  two  buildings  require  exactly  the  same  arrangement, — special  modi- 
fications being  necessary  to  meet  special  conditions.  The  different  types  have 
been  selected  with  care,  as  illustrating  the  variations  in  requirements  and  the  best 
means  of  meeting  them  in  buildings  differing  widely  in  construction  and  uses. 

Of  course,  it  is  not  to  be  understood  that  these  are  the  only  arrangements 
of  this  system  that  could  have  been  adopted  in  the  different  instances,  but, 
under  the  conditions  here  given,  they  appear  to  be  the  best.  To  the  reader, 
however,  these  illustrations  will  certainly  be  suggestive,  and,  it  is  trusted,  will 
make  still  more  evident  the  possibilities  of  the  system,  and  render  its  application 
more  intelligible.  The  important  factor  in  determining  upon  the  manner  in 
which  this  system  shall  best  be  introduced  in  a building  is,  first  of  all,  the  most 
convenient  location  of  the  apparatus,  which  in  turn  must,  of  course,  be  largely 
dependent  upon  the  method  of  distribution  of  air  to  be  adopted. 

Economically  considered,  it  is  almost  always  best  to  place  the  apparatus 
near  the  centre  of  the  building,  so  as  to  reduce  the  amount  of  ducts  or  piping 
to  the  minimum.  Steam  pipes  of  the  size  required  for  any  given  apparatus  can 
always  be  extended  at  less  expense  than  can  main  galvanized  iron  pipes  from  a 
given  apparatus ; therefore  it  is  better  to  carry  steam  to  the  apparatus  than  to 
carry  the  apparatus  to  the  steam. 

Upon  the  following  pages  the  various  arrangements  have  been  classified 
according  to  the  type  and  character  of  the  buildings  in  which  they  have  been 
installed.  All  illustrations  are  from  plants  introduced  by  this  Company,  and 
now  in  successful  operation  ; they  therefore  represent  actual  working  ex- 
amples of  the  application  of  this  system,  and  by  their  variety  bear  emphatic 
testimony  to  the  necessity  of  extended  experience  in  deciding  upon  the  best 
arrangement  to  be  adopted. 


109 


m VENTILATION  and  HEATINGM 

ONE-STORY  BUILDINGS. 

So  far  as  their  construction  is  concerned,  the  simplest  of  all  structures 
requiring  ventilation  and  heating  are  one-story  buildings,  such  as  mills,  shops 
and  exhibition  buildings.  But  no  other  form  of  building  has  so  large  an 
amount  of  wall  and  roof  surface  per  cubic  foot  of  enclosed  space,  or  such  high 
and  extended  rooms;  in  fact,  such  a building,  as  a rule,  forms  only  a single 
room.  As  a consequence  the  most  efficient  system  is  necessary  ; it  is  not  alone 
sufficient  that  the  apparatus  shall  be  large,  to  allow  for  the  excessive  heat  loss 
from  the  building,  but,  above  all,  the  arrangement  of  the  distributing  ducts 
must  be  such  as  to  most  .economically  utilize  the  heat  supplied ; for  underheating 
at  the  floor  and  overheating  above  is  one  of  the  most  natural  consequences 
of  an  imperfect  system  of  distribution.  Under  such  circumstances  the  appa- 
ratus itself  is  frequently  condemned  as  having  insufficient  capacity,  when  the 
trouble  lies  entirely  in  the  manner  in  which  the  heated  air  is  delivered  to  the 
building. 

In  buildings  of  this  type  the  principal  provision  is  to  be  made  for  the 
heating,  for  the  occupants  are  generally  separated,  and  the  air  supplied  for 
heating  will  answer  all  the  requirements  of  ventilation.  But  it  is  nevertheless 
necessary  that  they  should  be  provided  with  fresh  air  in  sufficient  quantity. 
One  of  the  inherent  virtues  of  this  method  of  heating  is  that  it  ensures  such 
supply.  As  the  air  provided  is  generally  in  excess  of  that  required  for  ventila- 
tion, increased  economy  can  be  secured  by  using  over  again  a portion  of  the 
previously  heated  air.  This  may  be  done  by  arranging  dampers  or  doors  so 
that  part  of  the  air  entering  the  heater  is  drawn  from  out  of  doors  and  part,  or, 
if  desirable,  the  whole  from  the  room.  In  fact,  in  the  ordinary  manufactory 
the  common  practice  is  to  nominally  take  the  entire  air  supply  from  within  the 
building.  This  does  not  result,  as  might  be  supposed,  in  a total  lack  of  ventila- 
tion, for  a very  considerable  amount  of  outward  leakage  takes  place  through 
the  walls  and  around  windows  and  doors.  Sufficient,  indeed,  to  cause  a similar 
inward,  but  imperceptible,  leakage  at  other  points  in  such  quantity  as  to  result 
in  a comparatively  frequent  change  of  air  within  the  building. 

One  of  the  greatest  difficulties  in  a building  of  this  character  is  to  heat  it 
rapidly  in  the  morning,  after  it  has  cooled  during  the  night.  No  other  system 
can  so  completely  and  rapidly  meet  this  requirement  as  that  here  presented. 
When  it  is  desirable,  the  engine  may  be  run  slowly  all  night,  and  the  building 
maintained  at  a moderate  temperature.  The  exhaust  from  the  engine  being 
used  in  the  heater,  no  expense  is  entailed  for  motive  power. 


1 10 


GRANT  LOCOMOTIVE  WORKS,  BOILER  SHOP,  CHICAGO,  ILL  * 
As  illustrated  in  Fig.  55,  this  building  is  of  the  simplest  type  of  modern  one- 
story  shop.  Its  width  demands  light  at  the  centre,  which  is  provided  by  the 
monitor,  the  introduction  of  which,  however,  has  a marked  influence  in  deter- 
mining the  method  of  hot  air  distribution  to  be  introduced. 

As  a rule,  it  is  undesirable  to  attempt  to  place  the  piping  on  one  side  only 
and  blow  the  air  across  such  a building,  because  of  its  tendency  to  rise  to  the 
monitor  in  the  centre.  The  principle  generally  followed  is  to  discharge  it 
entirely  around  the  building  and  toward  the  outer  walls.  To  this  end,  the 
apparatus  is  placed  upon  a platform,  for  the  double  purpose  of  economizing 
floor  space  and  providing  for  the  natural  return  of  the  water  of  condensation 
to  the  boilers  without  the  use  of  a return  water  apparatus. 


Fig.  55.  Grant  Locomotive  Works,  Boiler  Shop,  Chicago,  III. 


By  this  arrangement  the  fan  is  enabled  to  discharge  the  air  directly  into  a 
line  of  horizontal  piping  extending  around  the  entire  building  at  some  distance 
from  the  walls.  At  proper  intervals  outlets  are  provided,  through  which  the  air 
is  delivered  in  such  a direction  as  to  strike  the  floor  near  its  intersection  with  the 
outside  walls.  The  most  vulnerable  point  is  thus  attacked,  and  a warm  barrier 
of  air  interposed  between  the  occupants  and  the  cold  walls. 

The  natural  course  of  the  air  thus  discharged  is  backward  along  the  floor 
to  the  centre  of  the  building,  where  it  rises  to  the  monitor  above,  if  it  still 
retains  sufficient  temperature  to  cause  it  to  take  this  direction. 

A very  satisfactory  arrangement  in  a building  of  this  construction  consists 
in  supporting  the  apparatus  overhead  upon  the  trusses,  near  the  centre  of  the 
building.  Connection  is  then  made  to  a system  of  piping  located  and  discharg- 
ing exactly  as  here  shown. 

* Purchased  by  Siemens  & Halske  Electric  Co.,  of  America,  since  the  system  was  installed. 


VENTILATION  and  HEATING 


CARNEGIE  STEEL  CO.,  Ltd.,  HOMESTEAD  STEELWORKS,  MUN- 
HALL,  PA.  Notwithstanding  the  remarks  upon  the  preceding  page,  there  are 
certain  conditions  under  which  the  hot  air  may  all  be  supplied  from  one  side  of 
a building,  of  the  type  shown  in  Fig.  56.  Here  the  manufacturing  processes 
carried  on  within  the  building  have  much  to  do  with  the  success  of  the  arrange- 
ment. As  indicated  in  the  cut,  the  apparatus  is  placed  upon  the  floor  upon  one 
side  of  the  building,  and  midway  of  its  length. 


Homestead  Steel  Works,  Munhall,  Pa. 


From  the  outlet,  which  discharges  directly  upward,  the  pipe  branches  into 
two,  running  in  either  direction  nearly  the  entire  length  of  the  building.  In 
addition,  at  the  fan  outlet,  the  pipe  is  provided  with  a large  outlet,  so  located  as 
to  discharge  a large  volume  of  air  downward  and  directly  across  to  the  other 
side  of  the  building.  As  the  horizontal  pipes  extend  toward  the  ends  of  the 
building,  they  are  provided  with  outlets  upon  either  side,  delivering  the  air 
towards  the  floor  and  the  opposite  sides  of  the  building. 

Where  air  is  to  be  forced  long  distances  in  such  a building,  it  is  necessary 
that  its  individual  volume  be  large ; that  is,  that  for  a given  volume  of  air 
delivered,  a small  number  of  large  outlets  is  preferable  to  a large  number  of 
small  ones.  With  the  former  arrangement  the  body  of  air  seems  to  maintain  a 
certain  compactness  as  it  flows,  and  is  not  relatively  so  easily  dissipated  as  would 
be  the  case  with  a smaller  volume. 

Under  certain  circumstances  most  excellent  distribution  of  air  can  be 
seemed  by  forcing  it  in  quantity,  without  piping  for  a long  distance,  lengthwise 
of  such  a building.  Naturally,  with  such  an  arrangement,  where  the  minimum 
of  piping  is  used,  it  is  best  to  locate  the  outlets  so  that  the  air  will  be  delivered 
near  to  and  will  follow  the  line  of  the  side  walls. 


112 


« VENTILATION  and  HEATING* 

PITTSBURG,  COLUMBUS,  CINCINNATI  & ST.  LOUIS  RAILWAY 
CO.,  PASSENGER  CAR  PAINT  SHOP,  COLUMBUS,  O.  The  construction 
of  a car  paint  shop  is  materially  different  from  that  of  the  ordinary  one-story 
structure.  This  difference  is  most  evident  in  the  character  of  the  roof,  which  is 
covered  with  a series  of  monitors,  each  corresponding  to  a line  of  track  beneath. 
This  arrangement,  together  with  the  presence  of  cars  within  the  building,  practi- 
cally prevents  the  supply  of  air  by  forcing  it  horizontally  from  overhead 
outlets. 

Fig.  57  clearly  indicates  the  best  method  to  be  adopted.  Here  the  apparatus 
is  located  in  one  corner  of  the  building,  and  the  air  is  distributed  through  an 
overhead  system  of  galvanized  iron  piping,  extending  entirely  around  the 


inside  of  the  building  at  some  distance  from  the  walls.  Between  each  pair  of 
tracks  pipes  are  brought  down,  so  as  to  deliver  the  air  very  near  the  floor,  where 
it  naturally  spreads,  and  whence  it  gradually  rises  in  a well-distributed  mass. 

One  of  the  important  advantages  of  the  introduction  of  this  system  of 
heating  in  a building  used  for  this  purpose  lies  in  the  increased  rapidity  with 
which  the  cars  may  be  dried,  owing  to  the  large  volume  of  fresh  air  constantly 
coming  in  contact  with  the  paint.  In  other  words,  with  this  system  the  same 
number  of  cars  can  be  dried  in  a given  time  in  a smaller  building  than  by  the 
usual  methods  — certainly  an  important  element  in  deciding  upon  the  system  to 
be  adopted. 


1C 


VENTILATION  and  HEATING 


CHICAGO,  ST.  PAUL,  MINNEAPOLIS  & OMAHA  RAILWAY  CO., 
ROUNDHOUSE,  EAST  ST.  PAUL,  MINN.  The  proper  heating  of  a round- 
house  presents  a double  problem,  for  not  only  must  its  temperature  as  a whole  be 
kept  uniform  and  sufficiently  high,  but  provision  must  be  made,  where  heavy 
snow  storms  are  prevalent,  for  rapidly  melting  from  the  running  gear  of  the  loco- 


Fig.  58.  C.,  St.  P.,  M.  & O.  Ry.  Co..  Roundhouse,  East  St.  Paul,  Minn. 


motive  the  burden  of  snow  and  ice  with  which  it  is  so  frequently  encumbered 
when  first  returned  to  the  roundhouse  from  a long  run.  The  general  method 
of  solving  the  problem  is  made  evident  in  Fig.  58.  An  overhead  system,  with 
hot  air  discharged  toward  the  walls,  serves  for  the  general  warming,  while  special 
pipes,  to  be  used  when  desired,  conduct  large  volumes  of  air  to  the  pits,  where 
it  is  well  distributed  beneath  the  locomotives. 


VENTILATION  and  HEATING 


BUILDINGS  OF  MORE  THAN  ONE  STORY. 


As  the  number  of  stories  in  a building  increases,  so  do  the  complications 
in  the  manner  of  heating  the  same.  It  is  no  longer  a simple  matter  of  blowing 
the  air  from  the  fan  outlet  directly  into  the  single  floor,  or,  even  in  the  more 
extended  arrangement,  of  conducting  it  around  the  building  in  pipes  and  dis- 
charging it  at  suitable  intervals.  In  the  multi-storied  building  the  simplest 
arrangement  that  can,  in  many  cases,  be  sought  is  the  duplication  upon  each 
floor  of  the  scheme  that  prevailed  in  the  one-storied  building. 

There  is  this  to  be  said,  however,  in  favor  of  the  building  of  more  than 
one  story,  namely,  that  its  flat  ceilings  and  the  relatively  small  distance  from 
floor  to  floor  as  compared  with  the  height  from  floor  to  roof  in  a one-story 
building  make  the  matter  of  distribution  of  the  air  once  discharged  to  a given 
floor  very  much  easier.  With  smooth  ceilings,  unobstructed  by  beams,  shafting 
or  belting,  air  discharged  horizontally  at  high  velocity  just  beneath  them  may 
be  forced  for  long  distances,  as  to  the  opposite  side  or  end  of  the  room,  before 
its  volume  becomes  seriously  dissipated.  Of  course,  this  movement  reduces  to 
just  this  extent  the  necessity  of  distributing  pipes. 

But  where  beams  exist,  extending  below  the  ceiling,  opposing  their  faces  at 
right  angles  to  the  direction  of  the  air  movement,  the  currents  are  very  quickly 
broken  up,  and  it  is  impossible  to  compel  the  air  to  move  a great  distance 
beyond  the  outlet.  The  influence  of  shafting,  with  its  revolving  pulleys,  and  of 
a mass  of  moving  belts,  is  very  noticeable  in  a manufactory,  particularly  a 
textile  mill.  Under  such  conditions,  if  the  air  supply  openings  are  sufficiently 
numerous,  this  moving  machinery  plays  a most  beneficent  part,  and  thoroughly 
mixes  the  fresh  air  with  that  prevailing  in  the  room 

In  deciding  upon  the  arrangement  of  ducts  and  flues  in  a building  of  two 
or  more  stories  and  exceeding  50  feet  by  100  feet  in  floor  plan,  two  principal 
methods  appear.  First,  the  introduction  upon  each  floor  of  a complete  system 
of  overhead  piping,  extending  lengthwise  of  the  building,  with  outlets  at 
intervals,  the  pipes  upon  the  various  floors  being  fed  by  a single  stand  pipe  at 
some  convenient  point.  Second,  distribution  from  a number  of  vertical  flues 
placed  at  intervals  down  the  centre  or  along  the  side  of  the  building,  each  dis- 
charging to  each  floor,  and  all  being  supplied  by  a main  duct  in  the  basement 
or  lower  floor.  In  its  ideal  form,  this  is  the  arrangement  adopted  in  textile  and 
similar  mills  where  the  flues  are  built  of  brick  on  the  outside  of  the  building 
and  along  one  side.  Of  course,  it  is  evident  that  such  a construction  must  be 
decided  upon  before  the  erection  of  the  building  is  begun.  In  fact,  although  too 


115 


1 16 


VENTILATION  and  HEATING 


seldom  the  case,  it  is  very  desirable  that  the  location  and  arrangement  of  even 
a galvanized  iron  distributing  system  should  be  determined  before  work  has 
progressed  too  far.  Delay  in  this  matter  frequently  causes  great  inconvenience 
in  the  introduction  of  the  system,  which,  when  appreciated,  cannot  be  readily 
overcome.  This  is  particularly  true  with  reference  to  the  location  of  shafting, 
belting  and  machinery,  which,  in  many  cases,  might  just  as  well  have  been 
differently  arranged  had  it  been  known  that  interference  with  direct  lines  of 
distributing  pipe  might  have  been  avoided. 


GRANT  LOCOMOTIVE  WORKS,  MACHINE  AND  ERECTING 
SHOP,  CHICAGO,  ILL.*  In  the  modern  machine  shop  it  is  now  a common 
practice  to  introduce  an  intermediate  or  gallery  floor,  the  entire  height  of  the 
structure  being  made  sufficient  therefor.  Such  an  arrangement  in  one  of  its 
forms  is  shown  in  Fig.  59. 

The  portion  of  the  wing  shown  upon  the  right  is  fitted  upon  one  side  with 
an  extensive  gallery  upon  which  the  apparatus  stands.  Part  of  the  air  dis- 
charged therefrom  is  delivered  from  an  overhead  pipe  to  the  gallery  itself,  while 
the  main  floor  is  supplied  through  down-pipes  from  this  large  main  and  also  by 
special  outlets  direct  from  the  fans  themselves. 

The  wing  upon  the  left  was  designed  for  the  erection  of  locomotives,  and 
is  provided  with  tracks  and  pits.  The  system,  as  introduced  in  this  part  of  the 
building,  is  duplex,  part  of  the  air  being  supplied  above  head  level  by  risers 
against  the  wall  along  which  it  is  blown.  This  supply  is  supplemented  by  air 
delivered  to  the  pits  from  an  underground  duct  running  lengthwise  of  the 
building  just  back  of  the  pits.  By  these  two  methods  of  supply  the  warm  air 
is  well  distributed  at  floor  level,  a vital  feature  in  the  heating  of  such  a building. 
As  will  be  noted  from  the  illustration,  the  apparatus  is  duplex  and  of  the 
three-quarter  housing  type,  but  provided  with  a sheet  iron  lower  portion 
(not  seen  in  cut),  suspended  below  the  platform.  These  fans  are,  in  effect, 

full  housing  fans,  with  their  foundation  angle  irons  attached  part  way  up 

their  sides. 

Some  idea  of  the  magnitude  of  this  plant  may  be  formed  from  the  state- 
ment that  the  main  machine  shop  is  340  feet  long  by  1 10  feet  wide  and  66  feet 
high  at  its  highest  point.  The  wing  devoted  to  the  erection  of  locomotives 
measures  85  feet  by  300  feet  on  the  floor,  and  is  54  feet  high  to  the  ridge. 

Each  of  the  two  fan  wheels  in  the  apparatus  is  10  feet  in  diameter  by  5 wide, 

and  the  heater  contains  19,500  lineal  feet  of  one-inch  steel  pipe. 

* Purchased  by  Siemens  & H alske  Electric  Co.,  of  America,  since  the  system  was  installed. 


117 


VENTILATION  and  HEATING 


LINK  BELT  MACHINERY  CO.,  CHICAGO,  ILL.  The  true  type  of 
the  so-called  gallery  shop  is  clearly  represented  in  Fig.  60,  as  is  also  one  of  the 
most  convenient  methods  of  heating  the  same.  As  one  of  the  inherent  features 
of  such  a construction  is  a crane  travelling  down  the  centre  the  entire  length  of 
the  building,  it  is  obviously  impossible  to  carry  pipes  from  one  side  to  the  other 
unless  they  are  placed  underground  or  run  up  overhead.  Even  the  latter 
arrangement  is  frequently  impracticable. 

The  size  of  such  a building,  however,  generally  warrants  the  introduction 
of  two  apparatus  in  the  manner  shown,  the  apparatus  and  piping  upon  one  side 
being  an  exact  duplicate  of  that  on  the  other.  Each  fan  is  provided  with  a 


EzvscJ 

Jr  jJc.  JJ/j 

Fig.  60.  Link  Belt  Machinery  Co.,  Chicago,  111. 


double  discharge,  so  that  a portion  of  the  air  is  discharged  into  the  overhead 
system,  whence  it  is  forced  toward  the  outer  walls  of  the  gallery,  while  the 
remainder  of  the  air  delivered  by  the  fan  passes  into  the  duct  beneath,  from 
which  the  lower  floor  is  similarly  supplied. 

This  arrangement  requires  but  little  room  for  the  apparatus,  while  the 
piping  is  so  located  as  to  be  entirely  out  of  the  way,  noticeably  so  in  the  case  of 
the  line  running  overhead  in  the  gallery.  The  direction  of  discharge  toward 
the  outer  walls  is  exactly  what  is  desirable  to  secure  its  proper  movement 
through  the  cooling  action  of  the  walls,  and,  altogether,  the  plant  harmonizes 
in  simplicity  and  symmetry  with  the  building  itself. 


118 


VENTILATION  and  HEATING 


GEO.  F.  BLAKE  MFC.  CO.,  EAST  CAMBRIDGE,  MASS.  In  the 
building'  just  illustrated  the  frame  was  entirely  of  iron.  In  Fig.  61  is  shown  a 
building  almost  identical  in  proportions,  but  framed  throughout  of  wood. 
While  the  arrangement  for  heating  and  ventilating  introduced  in  the  former 
would  have  operated  efficiently  in  the  latter,  nevertheless,  to  meet  certain  con- 
ditions upon  the  part  of  the  owners,  an  entirely  different  method  was  adopted. 

Here  it  was  desired  that  only  a single  apparatus  should  be  installed,  and 
that  this  should  be  located  beside  the  engine  and  boiler  room.  Accordingly,  a 
fan  with  three-quarter  housing  was  introduced  and  arranged  to  deliver  the 
heated  air  into  an  underground  duct. 

This  duct,  after  supplying  branches, 
one  to  its  right  and  one  to  its  left, 
upon  the  side  of  the  building  nearest 
the  apparatus,  was  carried  across  un- 
derground to  the  opposite  side  of  the 


Fig.  61.  Geo.  F.  Blake  Mfg 


. Co.,  East  Cambridge,  Mass. 


building,  where  it  delivered  the  remaining  volume  of  air  into  another  duct 
running  nearly  the  entire  length  of  that  side. 

From  these  side  ducts  rectangular  galvanized  iron  flues  were  carried  up, 
each  tine  having  openings  on  its  sides  about  nine  feet  above  the  main  and 
gallery  floors.  The  air  is  thus  discharged  longitudinally  along  the  walls. 
Owing  to  the  large  number  of  outlets,  a very  equable  distribution  is  secured, 
resulting  in  uniformity  in  temperature  and  ventilation.  So  far  as  the  apparatus 
itself  is  concerned,  its  location  is  by  far  the  most  desirable  for  economy  in 
attendance,  while  its  floor  area  is  manifestly  less  than  that  required  for  two 
apparatus  of  the  same  capacity. 


119 


VENTILATION  and  HEATING 


CAPEWELL  HORSE  NAIL  CO.,  HARTFORD,  CONN.  A somewhat 
unique  structure  is  shown  in  Fig.  62,  the  upper  portions  of  the  space  in  the 
centre  being  formed  into  a second  floor.  The  apparatus,  which  is  of  the  blow- 
through  type,  is  supported  upon  the  trusses  just  below  this  floor  and  midway 
of  the  length  of  the  building.  From  either  side  of  the  heater  there  extends  a 
horizontal  pipe  nearly  down  to  the  end  of  the  building.  Branch  pipes  from 
these  mains  are  carried  downward  and  outward  to  the  side  bays,  into  which  the 
air  is  directly  discharged,  none  being  delivered  to  the  centre  of  the  building. 


Fig.  62.  Capewell  Horse  Nail  Co.,  Hartford,  Conn. 


From  the  top  of  the  heater  another  pipe,  extending  upward,  supplies  a 
horizontal  main  with  its  series  of  outlets  for  the  second  floor.  Evidently,  both 
upon  the  main  and  the  second  floor,  the  apparatus  and  piping  occupy  the 
minimum  of  space. 

Here  the  location  of  the  apparatus  itself  had  a marked  influence  upon  the 
method  of  heating  to  be  adopted.  The  apparatus  is  almost  exactly  in  the 
centre  of  the  building,  and  is  arranged  to  take  its  supply  from  the  building  itself, 
when  desired.  When  so  doing  the  air  delivered  at  the  most  distant  points, 
that  is,  in  the  outer  bays,  is  gradually  drawn  inward  to  the  large  centre  bay, 
heating  it,  so  far  as  its  lesser  requirements  demand,  and  finally  passing  again 
through  the  fan.  Had  a less  extended  system  of  piping  been  adopted,  the 
tendency  toward  a vacuum  in  the  vicinity  of  the  fan,  although  scarcely  per- 
ceptible, would  have  extended  a powerful  influence  to  prevent  the  air  reaching 
the  extreme  ends  and  sides  of  the  building  before  its  return  to  the  fan. 


120 


GLENS  FALLS  PAPER  MILL  CO.,  FORT  EDWARD,  N.  Y.  The 
ready  adaptability  of  the  Sturtevant  System  to  meet  the  varied  requirements  of 
the  paper  mill  is  evidenced  in  Fig.  63,  which  represents  a thoroughly-equipped 
sulphite  pulp  and  paper  mill  of  large  proportions. 

In  the  wood  room,  shown  in  the  foreground  at  the  extreme  left,  is  located 
a large  apparatus,  arranged  to  heat  both  the  first  and  second  floors  of  this  build- 
ing, as  indicated,  and  also  to  supply  the  wet-machine,  digester  and  acid  houses, 
which,  in  their  respective  order,  adjoin  the  wood  room  on  the  right.  A second 
apparatus  of  still  greater  capacity  is  located  in  the  finishing  room,  shown  just 
over  the  bridge  in  the  illustration.  From  this  apparatus  the  first  and  second 
floors  are  supplied,  while  branch  pipes  extend  down  the  centres  of  two  of  the 


Fig.  63.  Glens  Falls  Paper  Mill  Co.,  Fort  Edward,  N.  Y. 

machine  rooms,  and  thence  across  the  beater  engine  room  to  the  large  machine 
room  on  the  right.  A third  and  smaller  apparatus,  shown  just  beyond  the 
larger  one  just  described,  supplies  still  another  machine  room  in  the  extreme 
background. 

In  the  case  of  the  machine  rooms  which  are  supplied  with  roof  ventilators, 
the  principal  duty  of  the  system  is  to  prevent  the  deposition  of  moisture  upon 
the  ceiling,  and,  therefore,  the  air  is  discharged  more  directly  in  its  direction. 
The  moisture-absorbing  quality  of  the  heated  air  enables  it  to  immediately  take 
up  and  render  invisible  all  vapor,  thus  preventing  the  usual  great  annoyance  from 
this  source.  When  desired,  an  apparatus  designed  for  supplying  other  buildings 
besides  the  machine  room  may  be  arranged  to  supply  cooler  air  to  the  latter,  as 
an  offset  to  the  heating  effect  of  the  drying  cylinders.  In  the  digester  and  acid 
houses,  as  well  as  in  the  grinding  room  in  a ground  pulp  mill,  the  ventilating 
and  moisture-absorbing  features  of  the  Sturtevant  System  are  indispensable. 


121 


122 


Fig.  64.  Whitman  & Barnes  Mfg.  Co.,  West  Pullman,  III. 


M VENTILATION  and  HEATING« 

WHITMAN  & BARNES  MFG.  CO.,  WEST  PULLMAN,  ILL.  It  is 
doubtless  evident,  from  what  has  preceded,  that  there  is  practically  no  limit  to 
extent  of  the  buildings  for  the  heating  of  which  the  Blower  System  may  be 
applied.  As  buildings  increase  in  size  the  question  becomes  still  more  pertinent 
as  to  whether  one  or  more  apparatus  should  be  installed.  There  certainly  is  a 
limit  at  which  the  cost  of  piping  and  ducts  for  a single  apparatus,  plus  the  cost 
of  the  apparatus  itself,  exceeds  that  for  two  apparatus  and  their  connecting 
piping,  for  with  the  former  arrangement  the  air  often  has  to  be  carried  long- 
distances  before  it  can  be  directly  applied  for  heating. 

The  question  of  the  number  of  apparatus  is,  therefore,  one  that  is  usually 
first  presented  in  the  case  of  an  extremely  large  or  complex  plant,  and,  further- 
more, one  that  demands  the  most  careful  consideration  from  an  economical 
standpoint.  A most  excellent  example  of  the  solution  of  such  a problem  is 
presented  in  Fig.  64.  Here  an  enormous  plant  consists  of  numerous  buildings 
of  varying  size,  construction  and  uses.  It  was  undesirable  to  carry  any  piping 
or  ducts  either  overhead  or  underground  between  the  buildings.  Exhaust  steam, 
produced  by  the  main  shop  engine,  was  to  be  utilized  so  far  as  possible. 

A careful  study  of  the  sketch  will  make  evident  the  general  scheme.  For 
the  main  structure  on  the  front  a single  apparatus  was  installed,  midway  of  its 
length,  in  a special  small  building  built  at  the  back.  An  underground  duct  from 
this  apparatus  supplies  a series  of  pilaster  flues,  also  upon  the  back  of  the 
building.  Each  flue  is  provided  with  outlets,  one  to  each  floor. 

The  central  heating  plant  next  to  the  engine  room,  the  position  of  which 
is  between  the  chimney  and  the  observer,  supplies  the  main  central  building, 
which  is  of  one  story  with  pitch  roof.  The  pipe,  supported  in  the  middle  of 
the  building  upon  the  roof  trusses,  discharges  the  air  at  intervals  downward  and 
toward  the  walls.  In  the  extreme  rear  a three-story  building,  requiring  heating 
only  in  the  upper  floor,  is  supplied  in  a similar  manner,  the  pipe  being  carried 
overhead.  Economy  in  galvanized  iron  distributing  pipe  would  have  dictated 
that  this  apparatus  should  have  been  placed  nearer  its  centre  of  distribution, 
rather  than  at  the  end  of  the  piping  system.  But  the  practical  difficulties  in  the 
way  of  so  locating  the  apparatus,  on  account  of  the  room  it  would  occupy, 
compelled  its  location  in  a single  special  building  adjoining  the  engine  house. 

The  general  arrangement  of  the  other  two  systems  is  substantially  the  same. 
In  both  of  these  latter  cases  the  apparatus  is  exceptionally  well  located  as  regards 
economy  in  the  distributing  pipe,  and  in  both  the  apparatus  is  installed  in  a 
building  constructed  for  the  purpose,  so  that  no  valuable  floor  space  within  the 
main  buildings  is  occupied. 


VENTILATION  and  HEATING 


C.  H.  MOULTON  & CO.,  BROOKFIELD,  MASS.  In  modern  shop 
construction  nothing  is  more  symmetrical  or  better  adapted  for  a simple  installa- 
tion of  a galvanized  hot  air  piping  system  than  the  frame  shoe  shop,  of  which 
a typical  building  is  presented  in  Fig.  65.  Flere  the  basement  is  substantially  a 
cellar,  the  centre  of  which  is  surrendered  to  the  heating  apparatus.  This  con- 
sists of  a three-quarter  housing  fan,  with  top  horizontal  discharge,  driven  by  a 
horizontal  engine,  and  drawing  air  through  the  heater. 

From  the  outlet  of  the  fan  extends  a system  of  piping  suspended  just 
beneath  the  first-floor  beams.  At  the  centre  of  the  ^ building,  and  at 
points  some  40  feet  from  the  ends,  are  carried  up  ; \ vertical  risers,  pro- 


Fig.  65.  C.  H.  Moulton  & Co.,  Brookfield,  Mass. 


vided  with  outlets  through  which  each  floor  is  supplied.  The  central  pipe  is 
arranged  with  four  outlets  upon  each  floor,  so  that  the  discharge  is  at  an  angle 
of  45°  with  the  walls.  The  end  risers  have  each  only  two  outlets  on  a floor 
from  which  the  air  is  forced  toward  the  adjacent  corners. 

The  enormous  glass  area,  the  rather  open  construction  and  the  numerous 
employees,  seated  in  large  numbers  near  the  walls,  demand  the  maximum 
supply  of  warm  air  and  the  greatest  care  in  its  distribution,  which  latter  is  best 
secured  by  the  arrangement  shown. 

Under  other  circumstances  the  pipes  might  have  been  placed  against  one 
wall,  with  outlets  arranged  both  to  discharge  along  the  wall  and  across  the 
building. 


124 


VENTILATION  and  HEATING 


PELZER  MFG.  CO.,  PELZER,  S.  C.  In  no  class  of  manufacturing 
buildings  has  the  adaptability  of  the  Blower  System  been  more  carefully  con- 
sidered than  in  the  textile  mills;  and  yet  this  is  but  natural  when  the  perfection 
of  all  appointments  in  such  structures  is  considered.  The  general  similarity  of 
construction  in  buildings  of  this  character  has  greatly  facilitated  the  standardizing 
of  details  in  connection  with  the  heating,  ventilating  and  moistening  system. 

Modern  mill  construction,  as  exemplified  in  the  textile  mill,  is  generally 
considered  to  be  evidenced  in  brick  walls,  numerous  and  large  windows,  wooden 
floor  framing  consisting  of  large  timbers  extending  across  the  mill  at  intervals 
of  about  10  feet,  supported  by  the  walls  and  by  wooden  columns,  the  floor 
A being  of  3 or  4-inch  plank  with  1-inch  top  finish.  Such  construc- 
^ N tion  is  simplicity  itself. 


41: 


WOMi 


'*WRpsjpw 

3MJJrraMb)3i<  111' 


5333U 


q " 1 . - * 

■ mm  asa  fflsaa 


-1  -1  n '.  3 i a 

al  m in 


■333  „ 


JH 


JtT“ 


a:mi!'HJ«t33ajjr3aBHua  ink 

/.Off*'1  ‘ Lockwood  Gr)*n«{><& 


Fig.  66.  Pelzer  Manufacturing  Co.,  Pelzer,  S.  C. 


The  uniform  size  and  arrangement  of  the  machines  within  such  a building 
naturally  compels  the  preservation  of  straight  and  ample  passageways  between 
the  individual  machines,  as  well  as  around  them  next  to  the  walls.  Evidently 
there  is  no  practical  opportunity  for  the  introduction  of  heating  flues  anywhere 
within  the  building,  because  of  their  serious  interference  with  such  uniformity. 
But  the  brick  walls  present  a most  convenient  location  for  tlues  of  the  requi- 
site area. 

In  one  of  the  forms  adopted,  such  tlues,  projecting  outward  from  the  build- 
ing, as  illustrated  in  Fig.  66,  are  placed  along  one  side  of  the  structure  only, 
and  at  intervals  of  40  to  70  feet,  according  to  the  character  and  construction  of 
the  building.  In  the  basement,  or  ground  floor,  nearly  midway  of  its  length, 
is  located  the  apparatus,  usually  of  the  type  known  as  the  three-pulley  rig,  as 
shown  in  Fig.  53,  so  arranged  that  the  fans  may  be  driven  by  the  mill  engine 
during  the  day,  and,  if  necessary,  during  the  night  by  the  special  fan  engine 
provided  for  the  purpose. 


VENTILATION  and  HEATING 


Fig.  68. 


Extending  along  the  floor  upon  which  the  apparatus  stands,  or  beneath  it, 
if  desired,  is  a brick  duct  formed  upon  one  side  by  the  wall  of  the  building 
itself.  This  duct,  in  its  most  approved  type,  forms  in  section  what  is  known 
as  a quadrant  arch,  as  shown  in  Fig.  67.  Connection  from 
this  duct  is  made  with  each  pilaster  flue,  the  duct  being 
gradually  reduced  in  area  as  air  is  thus  discharged  from  it. 

The  flue,  as  will  be  noted,  is  also  decreased  as  it 
extends  upward,  to  compensate  for  the  air  delivered  to  the 
various  floors.  Its  general  construction  must  be  evident  in 
Fig.  67.  At  a sufficient  distance  below  the  floor  beams, 
to  avoid  weakening  the  construction,  outlets  are  provided 
from  this  flue  into  each  of  the  floors. 

Each  opening,  in  turn,  is  fitted  with  a special  damper 
of  the  type  presented  in  Fig.  68.  This  consists  of  a cast- 
iron  frame  bricked  into  the  wall,  and  sufficiently  strong  to 
prevent  weakening  the  same.  Pivoted  at  the  top  of  this  frame,  and  swinging 
inward,  is  a sheet-iron  plate,  serving  the  double  purpose  of 
damper  and  deflector,  and  adjustable  by  a worm  on  the  end  of 
the  vertical  rod  acting  upon  a gear  upon  the  damper  axis  to 
move  it  to  any  desired  position.  The  rod  extends  down  to 
within  easy  reach  of  the  operative. 
gp  Evidently  the  result  of  such  an  arrangement  of  the  Stur- 

tevant  System  in  connection  with  a building  of  the  character 
described  is  to  provide  the  most  excellent  opportunity  for  success- 
ful heating  from  one  side  of  the  building  only.  The  smooth 
ceilings,  without  beams  to  interfere  with  the  movement  of  air 
directly  across  the  building,  make  it  possible  to  fully  supply  the 
side  farthest  from  the  flues,  while  the  moving  pulleys,  belting  and 
shafting  which  intervene,  fortunately  present  just  enough  opposi- 
tion to  sufficiently  break  up  these  air  currents  and  thoroughly  mix 
the  air  throughout  the  room.  Although,  condi- 
tions permitting,  it  is  usually  advisable  to  place 
the  flues  upon  the  least  exposed  side  of  the  build- 
ing and  discharge  the  air  toward  the  colder  side, 
nevertheless,  in  practice,  the  effect  of  location  FiG.  67. 

of  flues  is  seldom  perceptible  in  such  a structure.  The  entire  subject  of 
heating,  ventilating  and  moistening  mills  is  exhaustively  treated  in  a special 
catalogue. 


126 


VENTILATION  and  HEATING 


PACIFIC  MILLS,  LAWRENCE,  MASS.  In  the  arrangement  just  de- 
scribed each  individual  flue  supplies  heated  air  to  each  of  the  floors  of  the 
building.  A somewhat  different  arrangement  is  presented  in  Figs.  69,  70  and 
71.  In  this  latter  building,  which  was  designed  distinctively  as  a yarn  mill,  no 
projecting  pilaster  flues  were  introduced,  but  each  pier  between  the  windows 
along  one  side  of  the  building  was  provided  with  an  internal  rectangular  tile 


lining  serving  as  a flue,  and  as 
supplies  air  to  only  a single 
third  flue  supplies  the  same 
apart,  this  brings  the  openings 
even  more  numerous  than  with 
ter  arrangement.  Evidently 
in  a building  of  four  stories  ^ 
the  openings  would,  under 
similar  conditions,  be  40  feet  (i; 
apart.  Each  flue  open 
ing  is  fitted  with 


a special  form 
of  damper 
some- 


indicated  in  Fig.  70.  Each  individual  flue 
floor,  so  that,  there  being  three  floors,  every 
floor.  As  the  piers  are  located  10  feet 
on  each  floor  30  feet  apart,  making  them 
the  ordinary  pilas- 


it"' 

' v\"V.  ► ..  ■ 

f.P.Sheldon  Mill  Architect 
Oind  Engineer  ‘Providence  P./. 


Fig.  69.  Pacific  Mills, 
Yarn  Mill,  Lawrence,  Mass. 


what  different  in  construction  from  that  already  shown  in  Fig.  68. 

This  arrangement  of  flues  avoids  the  break  in  architectural  harmony 
resulting  from  the  introduction  of  the  pilaster  flues,  but  at  the  expense  of 
greater  multiplicity  in  flues  and  openings  and  in  greater  opportunity  for  loss 
of  heat,  which  is,  however,  materially  reduced  by  the  use  of  the  flue  linings. 
Each  flue  connects  at  its  base  with  the  main  horizontal  duct,  of  which  the 
building  wall  forms  one  side.  The  top,  which  is  arched  in  form,  is  constructed 


127 


VENTILATION  and  HEATING 


of  corrugated  sheet  iron,  covered  level  with  cement.  Such  an  arrangement  is 
both  strong  and  serviceable,  and  is  to  be  preferred  substantially  in  this  form 
wherever  the  duct  has  to  be  excavated.  Another  scheme  of  top  covering  con- 
sists in  laying  brick  upon  tee  irons  extending  at  proper  intervals  across  the  top 
of  the  duct.  As  is  evident  in  Fig.  71,  reduction  in  area  as  the  duct  progresses 
is  in  part  secured  by  raising  the  level  of  its  bottom,  which,  in  consideration  of 

the  cost  of  excavation,  is 
more  economical  than  low- 
ering the  top.  Under  all 
conditions  the  duct  should 
be  kept  as  nearly  square  in 
cross  sections  as  the  circum- 
stances will  permit,  thereby 
saving  material  and  reduc- 
ing the  superficial  area  and 
the  losses  by  friction  of 
moving  air,  which  would 
be  incurred  by  any  other 
form. 

The  apparatus,  which  is 
located  about  midway  of 
the  length  of  the  mill,  is  of 
the  duplex  type,  each  fan 
being  driven  by  its  indi- 
vidual engine  and  the  entire 
apparatus  being  located  in 
FiG-  71.  an  independent  building. 

The  absence  of  a basement  under  the  mill  is  a sufficient  explanation  for  this 
location.  The  underground  ducts  from  the  two  fans  unite  before  they  pass 
beneath  the  mill  wall  and  are  here  provided  with  a swinging  damper,  so  arranged 
as  to  automatically  regulate  the  pressure  and  volume  of  air  discharged  from 
each  fan,  and  to  further  close  immediately  the  duct  from  either  fan  in  case 
it  is  shut  down. 

The  duct  extending  from  the  apparatus  toward  the  extreme  right-hand  end  of 
the  mill,  as  presented  in  the  illustration,  supplies  the  picker  house,  which  is  there 
located,  and  which,  owing  to  the  character  of  the  process  carried  on  within  it, 
requires  an  exceptionally  large  volume  of  air  for  the  double  purpose  of  maintain- 
ing the  temperature  and  making  good  the  amount  withdrawn  by  the  picker  fans. 


128 


VENTILATION  and  HEATING 


ELECTRICITY  IN  TEXTILE  MILLS.  The  presence  of  frictional  elec- 
tricity, generated  by  the  motion  of  belts,  pulleys,  running  stock  and  machinery, 
is  a source  not  only  of  annoyance  but  of  positive  loss  to  mill  owners.  In  card- 
ing and  spinning  particularly,  electricity  has  the  effect  of  causing  a change  of 
several  numbers  in  the  yarn  and  as  much  as  three  per  cent,  in  the  weight, 
weakening  the  yarn  and  causing  it  to  snap  and  break ; while  the  quality  and 
width  of  woven  goods  is  noticeably  affected.  Futile  attempts  have  been  made 
to  conduct  away  this  troublesome  electricity,  but  all  parts  of  a machine  cannot 
be  properly  connected  for  the  purpose,  and  a resulting  residue  of  electricity  is 
sure  to  make  itself  known.  It  is  well  understood  that  on  moist  days,  by  atmos- 
pheric conduction,  the  electricity  escapes  as  fast  as  produced ; while  on  dry  days 
it  is  insulated  in  belt,  machine  and  stock,  and  cannot  escape  into  the  air,  for  dry 
air  is  a poor,  while  moist  air  is  a good,  conductor  of  electricity.  Moisture  evi- 
dently plays  a very  important  part  in  electrical  troubles,  and  various  attempts 
have  been  made  to  imitate  the  action  of  the  moist  atmosphere  by  admitting 
water  to  the  mill  rooms  on  dry  days.  The  effect  which  moisture  in  the  air  has 
upon  electrification  in  the  rooms  appears  to  be  dependent  upon  the  relative 
humidity  in  the  mill  rooms.  The  amount  of  moisture  which  the  air  will  absorb 
depends  upon,  and  increases  with,  its  temperature.  With  the  relative  humidity 
above  a certain  per  cent.,  no  trouble  is  experienced ; as  this  per  cent,  decreases, 
the  electricity  makes  its  appearance  and  grows  more  and  more  annoying. 

A careful  consideration  of  these  statements  will  satisfactorily  prove  that  the 
whole  question  of  escaping  from  electrical  trouble  will  be  found  in  the  matter  of 
relative  humidity.  If  there  is  sufficient  moisture  in  the  atmosphere,  there  is  no 
trouble ; if  there  is  not  sufficient  moisture,  electricity  always  appears. 

As  moisture  depends  upon  the  currents  of  air  to  distribute  it,  no  better 
means  can  be  found  than  the  Sturtevant  System  for  obtaining  the  required 
results.  While  doing  efficiently  its  duty  as  a heating  and  ventilating  medium, 
the  air  may  be  moistened  to  any  desired  degree  by  sprays  or  evaporating  pans 
in  the  passages  from  the  heater  to  the  rooms.  The  exact  humidity  of  the  air 
may  be  noted  by  a hygrometer,  and  regulated  to  the  closest  degree.  With  an 
average  temperature  of  70°  to  80°  in  the  room,  the  per  cent,  of  humidity  need 
not  exceed  70.  This  will  insure  a comfortable  atmosphere,  and  will  absolutely 
prevent  the  presence  of  any  electricity.  The  mere  benefit  from  this  particular 
source  will  repay  any  enterprising  owner  for  introduction,  in  these  days  when  a 
saving  of  a fraction  of  a cent  per  yard  is  of  vital  importance.  But  with  the  addi- 
tional advantage  of  an  efficient  heating  and  ventilating  apparatus,  controllable 
under  all  conditions,  there  can  be  no  hesitation  as  to  the  desirability  of  the  system. 


129 


mm VENTILATION  and  HEATINGM 

OFFICE  AND  MERCANTILE  BUILDINGS. 

In  many  respects  the  mercantile  building  does  not  differ  greatly  in  its 
arrangement  and  requirements  from  the  factory  or  shop.  As  a rule,  large  open 
floors  exist,  and  the  attendants  are  reasonably  well  separated.  But  to  a greater 
extent  than  in  the  case  of  the  factory,  the  side  and,  frequently,  the  rear  walls 
are  blank,  because  of  abutting  buildings;  in  fact,  it  is  almost  universally  true 
that  the  store  is  most  exposed  upon  the  front ; but  show  windows,  with  their 
inner  sash  or  partitions,  often  serve  as  separate  air  spaces  in  a very  beneficial 
manner  to  prevent  the  passage  of  heat. 

In  large  wholesale  houses  there  is  seldom  any  obstruction  above  the  level 
of  the  tables  or  counters ; but,  in  some  instances,  shelving  is  carried  well  up  to 
the  ceiling.  Evidently  it  is  essential,  in  intelligently  planning  a heating  and 
ventilating  system  for  such  a building,  that  the  final  internal  arrangements  be 
known.  Owing  to  the  independent  rental  of  individual  floors  in  a building  of 
this  character,  it  is  frequently  the  case  that  any  information  regarding  the 
arrangements  within  the  room,  or  even  the  business  to  be  pursued,  cannot  be 
ascertained  in  advance.  Under  such  circumstances  the  general  scheme  can 
usually  be  laid  out  so  as  to  provide  for  easy  additions  in  the  way  of  galvanized 
iron  distributing  pipe. 

In  the  majority  of  cases  overhead  distribution  is  to  be  preferred,  the  air  be- 
ing discharged  from  flues  in  the  inner  walls  toward  the  colder  and  exposed  sides 
of  the  building.  With  a sufficient  supply  of  air,  ventilating  flues  are  not  necessary. 

The  oflice  building  is  a distinctive  feature  of  the  modern  city.  Its  numerous 
rooms,  of  various  sizes,  are  all  designed  for  a particular  class  of  occupants.  As 
a rule,  the  air  space  provided  per  occupant  is  large,  so  that  a fulfilment  by  the 
Blower  System  of  the  requirements  of  heating  is  certain  to  incidently  provide 
an  ample  supply  of  air  per  capita  for  all  purposes  of  ventilation.  The  sedentary 
occupation  of  those  for  whom  provision  is  made  makes  it  necessary  that  a fairly 
high  and  equable  temperature  be  maintained  throughout  the  building. 

It  is  evident  that  whatever  the  character  of  the  heating  and  ventilating 
system,  the  control  of  the  same  for  individual  rooms  must  either  be  placed  in 
the  hands  of  the  occupants  thereof,  or  must  be  independently  controlled  for 
them,  as  by  means  of  thermostats.  Owing  to  the  usual  excess  of  air  supply 
when  heating  is  required,  as  well  as  to  the  complications  incident  to  the  intro- 
duction of  a hot  and  cold  system  in  a building  of  so  many  small  rooms,  this 
latter  arrangement  is  seldom  introduced.  It  is,  however,  usually  a simple  matter 
to  apply  it  only  to  certain  apartments  in  which  the  requirements  demand  it. 


130 


VENTILATION  and  HEATING 


“ BOSTON  STORE,”  PROVIDENCE,  R.  I.  This  building,  which  is 
owned  by  the  Callender,  McAuslan  & Troup  Co.,  is  devoted  to  the  purposes  of 
a wholesale  and  retail  dry-goods  and  department  store  and  serves  as  a most 

excellent  example  of  a class  of  which  a considerable 
number  have  been  equipped  with  the  Sturtevant 
System  in  the  large  cities  of 
the  country.  Fig.  72  pre- 
sents a clear 
conception 


Fig  72.  “ Boston  Store,”  Providence,  R.  l. 

of  its  character  and  appearance  as  well  as  of  the  location  of  the  apparatus  and  the 
general  method  of  application.  In  the  case  of  a retail  store,  the  constant  passing 
of  the  customers  in  and  out  makes  it  extremely  difficult  to  maintain  the  portion 
near  the  entrance  at  even  a moderately  comfortable  temperature.  This  problem 
was  presented  in  connection  with  the  application  to  the  store  here  illustrated, 
and  in  fact  its  successful  solution  was  the  primary  result  sought  in  the  introduc- 
tion of  the  system.  Under  the  conditions  of  direct  heating,  the  attempt  is  usually 


131 


VENTILATION  and  HEATING 


made  to  prevent  the  entrance  of  cold  air  directly  to  the  store  by  the  introduction 
of  vestibules  with  double  or  triple  sets  of  automatically  closing  doors,  the  vesti- 
bule proper  being  provided  with  large  radiators.  In  effect,  however,  the  numerous 
doors  act  like  so  many  pump  valves,  and  the  partial  vacuum  frequently  pro- 
duced in  the  vestibule  compels  an  inward  rush  of  cold  air  when  the  outer  doors 
are  opened.  To  overcome  this  difficulty,  which  is  inherent  wherever  a direct 
heating  system  is  used,  it  is  evidently  necessary  to  maintain  within  the  vestibule 
such  pressure  of  air  as  to  compel  leakage  therefrom,  to  be  either  inward  or  out- 
ward as  the  case  may  be,  and  as  a natural  consequence  to  absolutely  prevent  the 
passage  of  cold  air  from  out-of-doors  directly  to  the  store  itself. 

The  illustration  serves  to 
show  the  relatively  great  vol- 
ume of  air  admitted  from  the 
basement  pipe  to  the  two 
large  vestibules,  each  being 
provided  with  four  large  regis- 
ters near  the  floor.  The  ap- 
paratus itself  is  located  in  the 
basement  at  the  extreme  front 
of  the  building.  The  fan, 
which  is  driven  by  an  inde- 
pendent electric  motor,  forces 
the  air  directly  through  the 
heater,  whence  it  enters  the 
distributing  pipe,  which  is 
carried  close  up  to  the  ceiling. 
As  a supplementary  means  of 
keeping  a store  of  this  character  warm,  it  is  necessary  to  discharge  a consider- 
able portion  of  the  heated  air  near  the  front.  This  may  be  readily  done  by  wall 
registers  above  head  level,  and  the  same  method  serves  for  the  heating  of  the 
entire  store,  the  registers  being  placed  in  vertical  flues  which  are  provided  at 
reasonable  intervals  along  the  side  walls. 

This  particular  store,  like  many  in  which  the  most  modern  improvements 
have  been  introduced,  is  equipped  with  counters  having  the  top  and  front  entirely 
of  glass.  Such  construction  absolutely  prevents  the  introduction  of  coils  or 
radiators  beneath  or  along  their  fronts  but  presents  a most  excellent  opportunity 
for  the  introduction  of  heated  air  under  the  Sturtevant  System.  Fig.  73  makes 
the  method  perfectly  clear.  This  is  far  preferable  to  admission  through  floor- 
registers,  which  always  serve  as  receptacles  for  dirt. 

132 


Fig.  73.  Detail  of  Counter. 


VENTILATION  and  HEATING  « 


AMERICAN  BELL  TELEPHONE  CO.,  BOSTON,  MASS.  The  gen- 
eral character  and  requirements  of  an  office  building  have  already  been  pointed 
out.  In  the  case  presented  in  Fig.  75  the  structure  illustrated  is  divided  in  its 
various  floors  into  rooms  of  widely  differing  sizes,  devoted  to  special  lines  of 
work,  but  practically  all  of  a more  or  less  clerical  character.  In  the  plan  of  the 
third  floor,  shown  in  Fig.  74,  the  general  form  of  the  building  and  the  arrange- 
ment of  the  rooms  is  made  evident. 

In  any  office  building  or,  in  fact,  in  any  structure  containing  numerous 
small  rooms,  the  multiplicity  of  flues  necessary  to  provide  independent  supply 
for  each,  together  with  the  frequent  diversity  of  arrangement  on  the  various 
floors,  practically  forbids  the  construction  of  individual  flues.  Under  certain 
circumstances  the  outer  walls  of  a building  with  symmetrical  window  arrange- 
ment may  be  utilized  for  the  introduction  of  flues ; but  it  is  seldom  that  such 
opportunity  is  presented. 

The  only  other  resort,  and  that  usually  adopted  for  distributing  the  air 
supply,  is  that  illustrated  in  this  instance.  At  a convenient  point,  adjacent  to 


Fig.  74.  American  Bell  Telephone  Co.,  Boston,  Mass.,  Third  Floor  Plan. 

the  main  corridor  and  as  nearly  central  as  possible,  a vertical  flue  is  provided. 
This  need  be  merely  of  sufficient  area  to  conduct  the  air  at  high  velocity  to  the 
various  floors ; in  fact,  owing  to  the  value  of  the  space  thus  occupied,  it  is  usual 
to  make  the  velocity  through  this  flue  practically  equal  to  that  at  which  the  air 
leaves  the  outlet  of  the  fan. 


133 


VENTILATION  and  HEATING 


Fig.  75.  American  Bell  Telephone  Co.,  Boston,  Mass. 


134 


VENTILATION  and  HEATING 


The  floor  heights  being  ample  in  this  building  there  was  introduced,  just 
beneath  the  corridor  ceiling  upon  each  floor,  a complete  horizontal  distributing 
system  of  galvanized  iron  pipe.  This  is  all  very  clearly  indicated  in  the  plan 
view.  Evidently  such  a system  must,  in  the  majority  of  cases,  be  rectangular  in 
cross  section,  seldom  exceeding  15  inches  in  depth.  Taking  its  supply  from  the 
vertical  flue,  each  one  of  these  independent  systems  delivers  air  to  all  of  the 
rooms  upon  its  respective  floor.  It  will  be  noted  that  numerous  opportunities 
are  offered,  as  at  the  connections  to  the  flue,  at  the  branch  or  a division  near  by, 
at  the  separate  branches  to  the  rooms  and  at  the  registers  themselves,  to  suffi- 
ciently lower  the  velocity  of  the  air  below  that  existing  in  the  flue,  to  secure  its 

entry  to  the  rooms  with  such  relatively 
slow  movement  as  to  cause  no  draughts 
whatever. 

The  finely -finished  interior  of  such  a 
building  naturally  demands  that  no  piping 
should  be  exposed  to  view.  It  is  cus- 
tomary, therefore,  to  finish  down  below 
the  pipe  and  its  branches  the  entire  width 
of  the  corridor,  making  thereby  a false 
ceiling,  but  little  below  that  of  the  adjoin- 
rooms,  so  slight,  indeed,  that  it  is  seldom 
noticeable.  Of  course,  the  character  of  such 
construction  I |'F|r|l  will  depend  upon  the  material  of  the  building 
itself, — usually  it  is  of  wood  or  wire  lath  and  plaster,  with  the  necessary  cross 
supports  of  wood  or  of  iron. 

In  the  case  under  consideration,  the  arrangement  of  the  overhead  duct  and 
its  branches  is  as  indicated  in  Fig.  76.  Here,  fireproof  construction  is  evident ; 
but  the  building  having  a steel  frame,  it  was  a comparatively  simple  matter  to 
introduce  both  the  ducts  and  their  connecting  branches  to  the  various  rooms. 
In  all  cases  the  registers  were,  because  of  these  conditions,  placed  close  to  the 
ceiling,  and  usually  directly  over  the  doors,  as  shown.  The  entire  system,  with 
the  exception  of  the  registers,  was  thus  rendered  entirely  invisible. 

The  apparatus,  shown  in  dotted  lines  in  the  plan,  was  placed  in  the  base- 
ment in  such  a position  as  to  enable  it  to  take  its  fresh  air  supply  through  a 
shaft  from  above  the  roof-line.  This  shaft  also  offered  an  excellent  opportunity 
for  the  introduction  of  special  filters  for  removing  from  the  air  the  minute 
particles  of  dust  that  are  so  much  to  be  avoided  in  a large  central  telephone 
station  such  as  exists  upon  the  upper  floor  of  this  building. 


^VENTILATION  and  HEATING 


PRISONS. 

The  requirements  of  a building  designed  for  the  imprisonment  of  criminals 
are  peculiar  to  itself.  In  the  most  advanced  construction  such  a building 
includes,  as  its  most  important  feature,  the  cell  room  or  rooms  variously 
arranged  according  to  the  ideas  of  those  in  authority,  but,  under  all  conditions, 
containing  a series  of  small  rooms  for  the  separate  confinement  of  the  occupants. 

Owing  to  the  character  of  the  inmates,  it  is  obviously  desirable  that  the 
heating  and  ventilating  system  should  provide  no  advantageous  opportunity  for 
escape,  while  the  occupation  of  the  cells,  during  at  least  one-half  of  the  twenty- 
four  hours,  requires  that  the  maximum  of  air  supply  per  occupant  shall  be 
provided.  The  separation  of  the  prisoners,  however,  is  such  that  the  supply  of 

air  necessary  to  ac- 


complish the  heat- 
ing under  ordinary 
conditions  is  suffi- 
cient to  meet  all 
requirements  per 
capita  for  the  pur- 
poses of  ventila- 
tion. 

The  cells  are 
usually  arranged  in 
tiers,  one  above  the 
other,  either  within 
an  outer  shell  or 
building,  or  else 
abutting  upon  a 
well  or  corridor  ex- 
tending up  several 
stories.  To  secure 
the  requisite  con- 
stant change  of 
air,  it  must  be 
evident,  there- 

Fig.  77.  Sectional  Elevation.  fore,  that  me- 

chanical means  should  be  employed,  and  that  both  plenum  and  exhaust  fans 
should  be  introduced  to  secure  the  necessary  equality  in  distribution. 


136 


I 


■ 


VENTILATION  and  HEATING 

WESTERN  STATE  PENITENTIARY,  ALLEGHENEY,  PA.  A model 
design  for  a cell  room  is  shown  by  elevation  and  plan  in  Figs.  77  and  78. 
Within  the  outer  shell,  with  its  narrow  and  high-barred  windows,  are  arranged 
four  tiers  of  cells,  each 
with  its  grated  door  open- 
ing upon  an  iron-floored 
gallery  and  facing  the 
outside  walls  of  the 
building,  but  about  1 5 
feet  therefrom.  These 
tiers,  arranged  in  two 
groups  running  lengthwise 
of  the  building,  are  sepa- 
rated at  their  backs,  and 
the  space  thus  found  is 
utilized  for  ventilating 
purposes. 

In  the  basement  of  each 
of  the  cell  houses,  which 
radiate  from  the  ro- 
tunda, are  located  four 
plenum  heating  appa- 
ratus, each  consisting 
of  a fan,  driven  by 
special  direct-connected 
engine,  and  arranged  to 
draw  the  air  from  above  FI(T  78.  Basement  Plan. 

the  roof  through  an  exterior  shaft  and  force  it  through  the  heater,  whence  it  is 
discharged  to  the  arched  duct  beneath  the  main  floor.  At  regular  intervals  the 
heated  air  is  discharged  from  this  duct  through  floor  openings  to  the  room  above. 

From  each  cell  at  top  and  bottom  the  air,  vitiated  by  its  passage  across  the 
person  of  the  occupant,  is  drawn  down  through  the  separating  space  at  the  back 
to  the  exhaust  fans  in  the  basement,  which  thus  create  a positive  circulation  and 
deliver  the  foul  air  above  the  roof. 

All  of  these  fans  are  over  12  feet  in  height,  and  are  operated  continuously. 
The  official  statement  of  those  in  charge  shows,  however,  that  since  their 
original  installation,  over  fifteen  years  ago,  less  than  $25.00  has  been  expended 
upon  them  in  the  matter  of  repairs. 


« I 4 

it  is3 


137 


VENTILATION  and  HEATING 


SCHOOL  BUILDINGS. 

As  a class  no  buildings  are  more  important  as  regards  their  ventilation  than 
those  used  for  educational  purposes.  In  such  buildings  are  gathered,  day  after 
day,  throughout  the  important  years  of  their  youth,  the  children  who  are  to  be 
the  living  forces  of  the  coming  generation.  Present  methods  of  instruction 
demand  that  they  shall  be  confined  within  their  respective  rooms  for  four  or 
five  hours  per  day,  and,  with  the  exception  of  a short  recess,  for  at  least  three 
hours  consecutively. 

The  harm  that  might  r&sult  from  exposure  to  a vitiated  atmosphere  for 
three  hours  only  once  or  twice  a week,  as  would  be  the  case  in  attendance  upon 
church,  entertainment  or  theatre,  is  evidently  slight  when  compared  with  that 
which  would  follow  from  exposure  under  the  continuous  conditions  of  school  life. 

As  compared  with  the  home,  the  store,  or  the  factory,  the  necessity  of 
ventilation  in  the  school  is  by  far  the  most  important,  because  of  the  compara- 
tively close  seating  of  the  scholars.  Even  in  the  best  schoolhouse  design  a 
space  allowance  of  250  cubic  feet  per  scholar  is  usually  considered  to  be  the 
maximum.  On  the  basis  now  generally  accepted  as  the  minimum  for  school- 
house  ventilation,  viz.,  a supply  of  30  cubic  feet  of  air  per  minute  per  pupil, 
this  initial  volume  of  250  cubic  feet  would  evidently  be  sufficient  for  a period 
of  only  a little  over  eight  minutes.  That  continuous  renewal  of  this  volume  is 
an  absolute  necessity  cannot  possibly  be  questioned,  when  we  consider  not  only 
the  health  of  the  children,  but  the  mental  vigor  that  should  exist  to  secure  the 
desired  ends  in  educational  matters. 

The  science  of  schoolhouse  design  and  construction  has  been  gradually 
crystallized  into  certain  well-acknowledged  principles.  For  middle  and  lower 
grade  classes  each  room  should  be  not  far  from  28  x 32  feet  in  floor  plan  and 
from  12  to  14  feet  in  height.  Such  a room  is  expected  to  accommodate  from 
50  to  55  scholars.  Special  attention  is  paid  to  the  size  and  location  of  windows, 
so  as  to  secure  the  proper  degree  of  lighting  and  from  the  most  desirable  direc- 
tion. As  a rule,  the  rooms  of  such  a building  are  symmetrically  grouped,  and 
it  is  seldom  that  the  height  of  the  structure  is  over  two  stories  with  basement, 
except  in  the  heart  of  a city  where  land  is  exceedingly  valuable.  In  the  modern 
eight-room  building,  as  is  also  the  case  where  the  the  number  of  rooms  is 
greater,  it  is  customary  to  provide  an  assembly  hall  upon  the  upper  floor.  The 
basement  is  also  frequently  utilized  for  instruction  in  manual  training.  High 
school,  academy  and  college  buildings,  with  their  provisions  for  recitation  and 
lecture  rooms,  laboratories,  libraries,  and  the  like,  are  usually  much  more 


138 


diversified  in  their  construction,  so  that  symmetry  of  arrangement  upon  the 
various  fioors  is  made  less  likely  to  be  found,  thereby  obviously  increasing'  the 
difficulty  of  introducing  vertical  fines  in  a simple  manner.  As  a rule,  however, 
such  buildings  are  of  brick,  with  internal  partitions  of  the  same  material.  This 
construction  readily  permits  of  the  introduction  of  both  heating  and  ventilating 
flues  in  the  most  advantageous  position,  namely,  in  the  inner  walls.  A base- 
ment of  ample  height  also  presents  an  excellent  opportunity  for  the  location 
of  the  apparatus. 

From  previous  remarks  it  must  be  evident  that  the  most  desirable  method 
of  heating  and  ventilating  an  ordinary  schoolhouse  must  be  by  the  introduction 
of  the  warm  air  through  registers  in  the  inner  walls  and  at  some  eight  feet 

above  the  floor.  Ventilating  flues  in  the  same  walls,  with  openings  near  the 

floor,  present  the  means  for  inducing  the  most  complete  distribution  of  air 
throughout  the  room  and  for  its  removal  when  its  intended  work  is  done. 

Care  should  be  exercised  in  the  selection  of  the  location  for  the  apparatus 
in  the  basement.  Its  position  should  be  such  as  to  require  the  minimum  of 
distributing  ducts  for  connection  to  the  flues ; while,  incidentally,  it  is  expedient 
that  it  be  placed,  if  possible,  under  a corridor  or  other  apartment  than  a school- 
room, in  order  to  avoid  even  the  possibility  of  noise  or  vibration  when  operated 
at  full  speed.  Unless  supplementary  coils  are  placed  at  the  bases  of  the  flues, 

the  apparatus  for  a school  building  should  always  be  of  the  hot  and  cold  type, 

in  order  that  the  temperature  of  any  given  room  may  be  adequately  regulated 
without  reference  to  that  of  others  in  the  building. 

As  the  height  of  the  basement  usually  permits  of  such  an  arrangement,  it 
is  customary  to  construct  the  system  of  ducts  of  galvanized  iron,  and  carry 
them  overhead  close  up  to  the  ceiling.  They  can,  however,  be  easily  introduced 
in  the  form  of  brick  conduits  underground,  and  where  the  hot  and  cold  method 
is  adopted  the  mixing  dampers  may  also  be  placed  underground,  at  the  bases  of 
the  various  flues,  and  arranged  to  be  operated  by  thermostat,  or  by  chain,  from 
their  respective  rooms. 

The  plenum  system  may  be  almost  universally  depended  upon  to  secure 
the  proper  ventilation  of  a school  building  without  the  accessory  of  an  exhaust 
fan,  although  the  latter  can  be  readily  introduced,  if  the  complexity  of  the 
building  and  the  vitiating  effects  of  chemical  and  other  laboratories  demand  it. 
Two  of  the  principal  methods  employed  in  the  introduction  of  the  Sturtevant 
System  in  school  buildings  are  illustrated  and  described  in  the  succeeding  pages. 

“ The  Ventilation  and  Heating  of  School  Buildings”  is  exhaustively  treated 
in  a special  catalogue  under  this  title,  which  will  be  sent  upon  application. 


VENTILATION  and  HEATING 


AGASSIZ  SCHOOL,  BOSTON,  MASS.  The  general  characteristics  of  a 
modern  fourteen-room  school  building  with  large  assembly  hall,  designed  for  a 
grammar  grade,  are  well  presented  in  Figs.  82,  83  and  84,  as  is  also  the  applica- 
tion of  the  hot  and  cold  double  duct  system  of  heating  and  ventilation.  In 
the  basement,  midway  of  the  length  of  the  building,  is  located  the  apparatus, 
consisting  of  two  fans,  driven  by  a horizontal  independent  engine  and  arranged 
to  force  air  through,  or  by-pass  it  above,  the  heater. 

From  the  end  of  the  heater  extend  two  systems  of  overhead  galvanized 
iron  ducts,  both  rectangular  in  section,  the  upper  conveying  cold,  and  the 
lower  hot,  air.  Both  of  these  ducts  connect 
with  the  bases  of  all  of  the  schoolroom  tines, 
there  being  introduced  at  each  point  of  con- 
nection a Sturtevant  mixing  damper  of  the 
form  already  illustrated  in  Fig.  11.  In 
addition,  air  is  discharged  from  the  hot- 
air duct  to  floor  registers  in  the  first- 
floor  corridor  and  in  each  of  the  cloak- 
rooms on  the  various  floors. 

The  compact  and  symmetrical 
arrangement  of  the  flues  in  the 
inner  walls  is  rendered  evident  in 
Fig.  82,  wherein  is  also  shown  the 
location  of  the  boilers  and  smoke 
flue.  Passing  up  these  flues,  which 
are  of  the  construction  shown  on 
the  left  of  Fig.  84,  the  warm  air 
enters  each  room  through  a grated 
opening  about  eight  feet  above  the 
floor.  The  appearance  and  loca- 
tion of  these  openings  is  clearly  indicated  in  Fig.  79,  the  grating  being  made  of 
one-eighth  inch  square  wire  with  one-inch  mesh.  Such  a grating  or  screen 
presents  greater  free  area  for  given  outside  dimensions  of  opening  and  at  less 
cost  than  a register  face. 

In  the  building  under  consideration  the  regulation  of  temperature  was  placed 
in  the  hands  of  the  occupants.  Each  mixing  damper  was  provided  with  a strong 
chain,  which  passed  up  the  flue  to  a point  below  the  screen,  where  it  was  carried 
over  a pulley  and  through  the  wall  just  below  the  chalk  rail.  A dial,  with 
inscriptions  and  arrows,  as  shown  in  Fig.  80,  served  as  an  indication  of  the 


Fig.  79- 


140 


VENTILATION  and  HEATING 


required  direction  of  movement  of  the  chain  to  secure  either  hot  or  cold  air,  while 
a pin  on  its  front  furnished  a simple  means  of  locking-  the  chain  when  once  in 
position.  This  system  could  have  been  arranged  equally 
well  for  the  regulation  of  temperature  entirely  by  means  of 
thermostats,  the  damper  being  fitted  up  either  as  shown  in 
Fig.  13  or  in  Fig.  14. 

Each  of  the  vent  tlues,  in  which  the  outlet  screens  are 
located  near  the  tloor,  was  provided  with  a special  shut-off 
damper,  placed  above  this  opening  and  arranged  to  be 
operated  by  chain  from  the  basement.  The  escape  of  air 
from  the  rooms  could  thus  be  conveniently  regulated  by 
the  janitor  according  to  the  external  conditions ; for  on 
extremely  cold  days  the  natural  discharge  of  air  through 
these  flues  would  frequently  be  in  excess  of  the  require- 
ments. The  arrangement  further  provided  the  simplest  means  for 
preventing  all  escape  of  air  from  the  building  during  the  night  and 
while  heating  up  in  the  morning.  All  of  the  ventilating  tlues  discharge 
above  the  roof  through  the  brick  stacks. 

It  is  sometimes  desirable  to  secure  a more  complete  distribution  of 
the  air  throughout  the  room  than  would  result  under  ordinary  condi- 
tions with  an  opening  in  some  enforced  location.  A 
=e--L:'..  ■ - diffuser,  of  the  type  shown  in  Fig.  81,  may  then 

be  employed  to  break  up  the  volume  of  air 
as  it  leaves  the  opening  and  produce  separate  cur- 
rents moving  in  diverging  directions. 

As  the  primary  adjustment  of  the  system 
should  provide  for  the  delivery  of  the  proper 
amount  of  air  to  each  room,  it  is  usually  undesir- 
able to  provide  any  means  whereby  the  occupants 
of  the  rooms  can  readily  reduce  its  volume.  Such 
shut-off  dampers  as  may  be  introduced  in  the 
system  are,  therefore,  arranged  to  be  operated  by 
the  janitor.  Ventilation  of  the  sanitaries  in  the  base- 
ment is  secured  during  the  operation  of  the  boiler 
by  the  aspirating  effect  of  the  boiler  flue,  around 
which  passes  the  air  direct  from  the  closets,  whence  it  is  conducted  by  under- 
ground ducts.  At  other  times  this  ventilation  is  maintained  by  the  heat  from 
a special  stove  placed  beneath  the  smoke  flue. 


141 


m' VENTILATION  and  HEATING 


MENOMINEE  HIGH  SCHOOL,  MENOMINEE,  MICH.  While  there  is 
in  various  school  buildings  comparatively  little  divergence  from  the  general 
scheme  of  air  admission  and  removal  previously  described,  there  is  usually 
presented  considerable  opportunity  for  variety  in  the  arrangement  of  the  appa- 
ratus and  distributing  ducts  in  the  basement.  A scheme  differing  in  many 
particulars  from  that  just  illustrated  is  shown  in  Fig.  85. 

Here  the  fan  is  of  the  three-quarter  housing  type,  with  large  outlet.  The 
engine  is  independent,  and  drives  the  fan  by  belt.  Placed  opposite  two  of  the 
basement  windows  are  two  tempering  coils,  arranged  to  utilize  the  exhaust  steam 
from  the  engine,  and  designed  to  simply  take  the  chill  off  of  the  air. 

Enclosed  in  a brick  chamber  in  front  of  the  fan  are  two  groups  of  heater 
sections  set  high  above  the  floor,  so  that  the  air  discharged  from  the  fan  may 
pass  either  beneath  or  through  them.  From  the  end  of  this  air  chamber  extends 
a system  of  individual  overhead  rectangular  galvanized  iron  pipes,  one  for  each 
of  the  vertical  heating  flues.  Each  pipe  is  so  arranged  at  its  connection  with 
the  air  chamber  that,  according  as  a damper  is  adjusted,  it  may  draw  its  air  from 
the  supply  that  has  passed  through  the  heater  or  from  the  space  beneath,  to 
which  is  delivered  the  cooler  air. 

Each  one  of  the  individual  dampers  is  arranged  to  be  operated  by  a ther- 
mostat, which  acts  in  harmony  with  the  changes  in  temperature  of  the  room 
with  which  the  pipe  and  its  respective  flue  connect.  By  this  thermostatic  action 
warm  or  cool  air  is  delivered  to  the  room  according  to  its  requirements,  and  it 
is  a simple  matter  to  maintain  the  room  temperature  within  a range  of  two 
degrees.  The  advantageous  features  of  this  general  design  lie  principally  in  the 
assembling  of  the  thermostats  in  the  air  chamber  and  in  the  avoidance  of  a 
double  system  of  ducts. 

The  ventilation  of  the  sanitaries  is  made  positive  and  ample  by  providing  a 
small  exhaust  fan,  driven  by  the  fan  engine,  and  arranging  a system  of  under- 
ground ducts  through  which  the  foul  air  is  drawn  to  the  fan  and  thence  forced 
to  the  space  around  the  boiler  stack.  In  these  sanitaries  the  heating  is  effected 
by  overhead  steam  coils  without  direct  supply  of  air.  The  exhaust  ventilation, 
however,  is  made  so  strong,  aided  by  the  plenum  effect  within  the  rest  of  the 
building,  that  all  leakage  is  inward  and  all  possibility  of  the  escape  of  foul 
odors  to  other  parts  of  the  building  is  avoided. 

When  the  construction  of  the  basement  will  permit,  the  warm  air  is  some- 
times discharged  into  a large  chamber  occupying  the  central  portion  of  the 
basement,  whence  it  escapes  through  openings  and  short  pipes  to  the  various  flues, 
there  to  be  heated  by  supplementary  coils  under  the  control  of  thermostats. 


142 


143 


Fig.  82.  Agassiz  School,  Boston,  Mass. 


144 


Fig.  8c  Agassiz  School, 
Boston,  Mass, 


urn 


.45 


Fig.  84.  Agassiz  School,  Boston,  Mass. 


146 


Fig.  8?.  Menominee  High  School,  Menominee,  Mich. 


HOSPITALS  AND  ASYLUMS. 

The  evidences  of  insufficent  ventilation  are  nowhere  more  pronounced  than 
in  building's  devoted  to  the  use  of  the  sick  and  diseased.  Constitutions  already 
weakened  are  very  quickly  rendered  still  more  susceptible  to  the  further  inroads 
of  disease  by  exposure  to  a vitiated  atmosphere.  The  marked  improvement  in 
the  healthfulness  of  such  buildings  where  good  ventilation  obtains  was  perti- 
nently shown  in  the  opening  chapter. 

Because  of  the  more  perceptible  benefits  of  pure  air  in  buildings  of  this 
character,  they  have  long  been  the  subject  of  thoughtful  study  as  to  the  best 
means  to  secure  the  desired  ends.  Long  before  efficient  systems  of  ventilation 
were  applied  to  other  buildings,  the  hospitals  of  this  country  and  of  Europe  were 
equipped  with  ventilating  devices  that  in  their  day  were  far  in  advance  of  those 
introduced  in  any  other  structures. 

In  no  buildings  should  the  ventilation  be  more  carefully  considered  in  the 
development  of  the  original  plans  than  in  those  of  the  class  under  consideration. 
The  intended  use  of  each  room  must  be  known,  the  arrangement  of  beds  in  the 
wards  should  be  determined,  and  even  the  character  of  the  diseases  which  are  to 
be  treated  in  the  various  wards  should  by  no  means  be  overlooked. 

In  the  thoroughly-equipped  hospital  of  the  present  day  there  is  always 
special  and  separate  provision  for  contagious  diseases,  almost  universally  in 
independent  buildings.  Evidently  the  maximum  ventilation  is  required  under 
such  conditions.  The  30  cubic  feet  per  person,  deemed  sufficient  in  the  school 
and  the  hall  of  audience,  becomes  utterly  inadequate  when  the  atmosphere  is 
laden  with  contagious  disease  germs.  From  a theoretical  standpoint  too  much 
air  cannot  be  supplied  under  these  conditions ; in  practice,  however,  it  frequently 
runs  up  to  100  cubic  feet  per  minute  and  over. 

To  secure  the  positive  supply  of  such  an  amount  naturally  demands  posi- 
tive and  mechanical  means.  In  the  hospital  of  moderate  size  the  plenum  system 
will  meet  all  requirements,  but  under  certain  circumstances,  in  more  complicated 
structures,  it  becomes  desirable  to  assist  its  action  by  exhaust  fans. 

In  the  majority  of  cases  the  occupants  of  asylums  are  supposed  to  be  in  a 
reasonably  healthy  condition,  so  far  as  the  general  functions  of  the  body  are 
concerned.  The  air  supply  per  capita,  therefore,  usually  need  be  merely  that 
provided  for  other  classes  of  buildings  devoted  to  similar  uses,  where  the  occu- 
pants gather  in  certain  rooms,  or  out  of  doors,  during  the  day  and  return  to  their 
dormitories,  or  individual  sleeping  rooms,  for  the  night.  Where  the  violently 
insane  are  confined  in  individual  cells  the  same  methods  apply  as  in  a prison. 


147 


VENTILATION  and  HEATING 


WALTHAM  HOSPITAL,  WALTHAM,  MASS.  In  its  application  to  a 
city  hospital  of  moderate  size  the  Sturtevant  System  is  shown  in  Fig.  86.  The 
wing  upon  the  right  in  the  illustration  is  divided  into  numerous  small  wards 
and  nurses’  rooms,  so  that  the  method  of  distribution  becomes  similar  to  that 
provided  for  an  office  building  or  a dwelling.  Owing  to  the  fact  that  the  build- 
ing was  of  so-called  mill  construction,  with  no  heavy  internal  partition  walls,  it 
was  necessary  to  supply  practically  all  of  the  fresh  air  and  remove  the  foul  air 
through  flues  built  into  the  exterior  brick  walls.  The  general  arrangement  of 
these  flues  upon  one  end  of  the  building  is  indicated. 

In  the  basement  is  located  a draw-through  apparatus,  provided  with  engine 


Fig.  86.  Waltham  Hospital,  Waltham,  Mass. 


for  motive  power,  when  steam  is  necessary  for  the  heating,  and  with  electric 
motor  for  propelling  the  fan  when  the  boiler  is  not  in  operation.  An  overhead 
system  of  galvanized  iron  ducts  in  the  basement  serves  to  distribute  the  air  from 
the  apparatus  to  the  bases  of  the  various  flues. 

In  the  other  wing  are  located  two  wards,  one  upon  either  floor,  and  both  of 
considerable  size.  These  are  heated  from  overhead  outlets,  as  indicated.  The 
air  is  forced  toward  the  end  of  the  room  farthest  from  these  outlets,  being 
generally  diffused  in  its  passage  and  finally  escaping  through  registers  at  floor 
level  and  nearly  beneath  the  supply  openings.  Thence  the  air  is  discharged 
above  the  roof.  In  more  complicated  arrangements,  and  particularly  in  con- 
tagious wards,  the  system  may  be  arranged  to  furnish  practically  every  bed  with 
an  independent  supply.  But  considering  the  rapidity  with  which  the  air  thus 
supplied  diffuses  itself  in  the  surrounding  atmosphere,  such  arrangements  are 
not  as  efficacious  as  would  at  first  appear. 


148 


VENTILATION  and  HEATING 


The  operating  room  of  a hospital  always  requires  an  extremely  high  tem- 
perature to  be  secured  at  almost  a moment’s  notice  when  an  accident  case  is 
suddenly  brought  in.  In  the  building  under  consideration  provision  was  made 
for  the  supply  of  a large  volume  of  hot  air  to  this  room,  whereby  its  temperature 
could  be  suddenly  raised  to,  and  maintained  at,  the  desired  degree.  Incidentally 
this  large  volume  of  air,  of  course,  provided  the  maximum  of  ventilation  at  a 
time  when  fresh  air  is  very  desirable. 


TROY  ORPHAN  ASYLUM,  TROY,  N.  Y.  As  already  indicated,  the 
hygienic  requirements  of  an  asylum  usually  differ  from,  although  they  some- 
times merge  into,  those  of  a hospital.  The  ordinary  asylum,  as  designed  princi- 
pally for  the  use  of  persons  otherwise  without  a home,  partakes  to  a certain 
extent  of  the  character  of  a dwelling  house  or  hotel,  but  usually  contains  a series 
of  dormitories  in  which  are  gathered  at  night  most  of  the  occupants  of  the 
building. 

A typical  building  or  series  of  buildings  of  this  class  is  illustrated  in  Fig. 
87.  Here  it  is  evident  that  an  extended  distributing  system  is  necessary,  and  it 
may  even  be  questioned  whether  a single  apparatus  will  be  most  satisfactory  for 
the  purpose.  As  will  be  noted  in  Fig.  88,  the  problem,  after  all,  resolves  itself 
into  the  question  as  to  whether  the  apparatus  shall  be  placed  in  the  building 
itself  or  in  the  boiler  and  power  house  at  the  rear. 


149 


VENTILATION  and  HEATING 


Here  was  a case  where  the  matter  of  attention  by  the  engineer  entered  as 
an  important  factor.  His  greatest  efficiency  could,  of  course,  be  best  secured 
by  massing  the  apparatus  under  his  control.  Hence  the  location  of  the  heating 
and  ventilating  apparatus  in  the  boiler  house.  Thence  the  air,  delivered  to  an 
underground  brick  duct  by  a three-quarter  housing  fan,  passes  beneath  the  centre 
building,  where  its  volume  is  divided,  a portion  passing  to  each  wing  through 
galvanized  iron 


pipes,  which  con- 
nect with  the  ends 
of  the  ducts,  and, 
rising,  are  carried 
overhead  in  the 
basement. 

The  internal 
partitions  of  the 
building  being 
principally  of 
wood,  the  vertical 
flues  were  con- 
structed of  gal-  "T 
vanized  iron. 


Fig.  88. 
Troy  Orphan 
Asylum, 
Troy,  n.  Y., 
Basement  Plan. 


Wherever  possible,  these  flues  were  made  rectangular  and  enclosed  in  the  parti- 
tions, but  in  the  majority  of  cases  they  had  to  be  carried  up  outside  of  the 
partitions,  and  false  work  breasted  out  around  them  to  give  the  proper  finish. 
In  other  cases  they  were  carried  up  in  the  corners  and  the  finish  extended 
diagonally  across  the  corner  outside  of  them. 

From  these  flues  the  air  is  admitted  at  the  usual  height  above  the  floor,  and 
allowed  to  escape  through  ventilating  registers  at  floor  level,  whence  it  passes  up 
to  the  attic  space.  Roof  ventilators  and  louvred  windows  provide  an  oppor- 
tunity for  it  to  finally  escape  to  the  outer  atmosphere. 

As  the  rooms  are  designed  for  various  uses,  and  are  diversified  in  their  size 
and  arrangement,  the  methods  of  distribution  were  adopted  to  suit.  The  system 
throughout  was  designed  to  supply  hot  air  only,  and  serves  its  purpose  well,  as 
the  air  space  per  occupant  is  such  that  for  the  mere  purposes  of  heating  the 
air  supply  per  capita  is  more  than  ample  to  meet  the  requirements  of  ventila- 
tion. It  must  be  evident,  however,  that  a hot  and  cold  system,  with  the  requi- 
site double  ducts  and  mixing  dampers,  could  have  been  introduced  if  it  had 
been  deemed  necessary. 


150 


mm VENTILATION  and  HEATING  M 


PUBLIC  BUILDINGS  AND  HALLS  OF 
AUDIENCE. 

Although  in  its  broadest  sense  the  expression  “ Public  Building”  evidently 
includes  a great  variety  of  structures,  yet,  as  ordinarily  employed,  the  term 
generally  refers  to  town  and  city  halls,  State  Houses,  court  buildings,  and  to  the 
buildings  used  for  the  meetings  of  a National  assembly.  In  all  the  buildings 
included  in  this  class  there  is  a similarity  in  design  and  construction,  such  that 
they  may  be  grouped  together  when  considering  their  ventilation  and  heating. 

The  characteristics  of  such  a building  are,  one  or  more  large  rooms  or  halls, 
used  as  assembling  places,  and  numerous  smaller  apartments  serving  practically 
the  same  purposes  as  similar  rooms  in  an  office  building,  the  application  of  the 
Sturtevant  System  to  which  has  already  been  discussed.  The  same  principles 
and  methods  hold  with  similar  construction  in  a public  building. 

TJie  assembly  rooms,  however,  offer  a somewhat  new  problem  in  heating 
and  ventilation.  In  the  well-equipped  modern  legislative  hall  the  seats  are 
usually  arranged  in  the  form  of  an  amphitheatre,  upon  levels  successively  rising 
toward  the  walls  most  distant  from  the  presiding  officer.  The  presence  of 
individual  desks  enforces  the  separation  of  the  occupants  much  as  in  a school- 
room, so  that  the  initial  air  space  per  capita  is  usually  large.  But  unlike  a 
schoolroom,  the  legislative  hall  is  frequently  occupied  for  many  hours  in  suc- 
cession, and  often  during  the  night,  when  the  effect  of  the  lighting  medium  has 
to  considered,  while  the  number  of  persons  present  is  constantly  changing  and 
sometimes  suddenly  augmented  by  the  crowding  of  the  galleries. 

Add  to  these  conditions  the  fact  that  even  in  a State  Legislature  there  is 
great  diversity  in  the  age,  health  and  home  surroundings  of  the  members,  while 
in  a National  assembly  in  a country  like  our  own  there  is,  in  addition,  the  most 
radical  difference  in  climate  between  the  parts  of  the  country  from  which  they 
come,  and  it  is  obvious  beyond  all  question  that  no  more  difficult  problem  in 
heating  and  ventilation  can  be  considered.  As  a rule,  the  treatment  of  such  an 
apartment  should  be  on  the  same  lines  as  that  of  a theatre,  with  well-distributed 
supply,  as  indicated  in  subsequent  illustrations  and  description. 

The  ordinary  hall  of  audience,  with  level  floor,  often  with  gallery,  but 
seldom  with  more  than  one,  presents  conditions  different  from  both  the  legisla- 
tive hall  and  the  theatre.  The  frequent  location  of  such  a hall  in  the  upper 
floor  of  a building,  with  numerous  offices  and  smaller  rooms  beneath,  has  a 
certain  influence  upon  the  possible  methods  of  heating  and  ventilation. 


151 


m VENTILATION  and  HEATING 


HERSEY  MEMORIAL  BUILDING,  BANGOR,  ME.  Although  not  so 
indicated  by  its  title,  the  building  illustrated  in  Fig.  89  is  a municipal  building, 
devoted  to  the  uses  of  a city  hall,  and  provided,  in  its  upper  story,  with  a large 
audience  hall  for  general  public  and  private  uses.  As  the  lower  portion  of  the 
building  is  subdivided  into  comparatively  small  rooms,  and  their 
treatment  is  substantially  the  same  as  in  an  ordinary  office 
K , , building,  it  has  been  the  endeavor  to  present  in  the 
cut  only  the  method  of  application  of  the  Sturte- 
vant  System  to  the  hall  itself.  As  will  be  noted, 
this  hall,  with  its  stage  and  galleries,  occupies  the 


Fig.  89.  Hersey  Memorial  Building,  Bangor,  Me. 


greater  portion  of  the  floor  upon  which  it  is  located.  The  floor  is  level,  pre- 
cluding the  ready  introduction  of  air  at  this  point.  It  is,  however,  admitted  at 
numerous  openings  on  each  side  of  the  hall  just  below  the  gallery,  and  also 
from  two  overhead  outlets  at  the  back  of  the  stage.  From  all  of  these  openings 
the  air  is  discharged  toward  the  centre  of  the  room,  thus  eventually  reaching 
ail  of  the  occupants  and  becoming  thoroughly  distributed.  The  ceiling  beneath 
the  balcony  presents  a most  excellent  surface  to  aid  in  forcing  the  greater  part 
the  air  toward  the  centre.  But  in  its  passage  a certain  portion  falls  and  supplies 
those  seated  at  floor  level,  while  a sufficient  volume  curls  up  over  the  gallery 
front  to  supply  its  occupants. 


152 


m VENTILATION  and  HEATING 


Ventilation  takes  place  at  numerous  points,  the  larger  volume  passing  in 
beneath  the  stage  through  its  grated  front  to  a large  ventilating  tine  at  its  back, 
and  thence  into  the  roof  space  and  the  tower.  Ventilating  registers,  placed 
against  the  walls  at  floor  level,  also  assist  in  the  removal  of  foul  air.  Unless 
actual  supply  through  the  floor  is  possible  in  a hall  of  audience  (under  which 
conditions  ceiling  ventilation  would  be  feasible),  it  should  be  the  aim  to  admit 
the  air  horizontally  at  as  low  a level  as  possible,  and  by  means  of  ventilation  at 
a still  lower  level,  to  prevent  the  overheating  of  the  galleries. 


Fig.  90.  Hersey  Memorial  Building,  Bangor,  Me.,  Basement  Plan. 


The  general  arrangement  of  the  apparatus  and  the  scheme  of  air  distribu- 
tion is  presented  in  Fig.  90.  The  apparatus  is  placed  near  a window,  whence  its 
supply  of  fresh  air  is  drawn.  The  heated  air  passes  through  an  extended  system 
of  overhead  galvanized  iron  ducts  in  the  basement  to  the  bases  of  the  various 
flues.  Most  of  those  for  the  audience  hall  are  located  in  the  outer  walls,  while 
those  for  the  lower  floor  are,  to  a considerable  extent,  formed  in  the  interior 
partition  walls. 

A special  small  fan  driven  by  water  motor,  but  not  shown  in  the  plan,  was 
also  installed  for  the  purpose  of  rendering  positive  the  ventilation  of  the  toilet 
rooms,  from  which  it  withdraws  a large  and  constant  volume. 

In  a building  of  this  character,  in  which  it  may  be  known  that  almost  with- 
out exception  the  hall  is  to  be  used  in  the  evening,  while  the  majority  of  the 
other  rooms  in  the  building  are  vacant,  it  is  sometimes  possible  to  arrange  to 
divert  some  of  the  air  from  the  office  portion  and  throw  it  into  the  hall,  but  the 
possibilities  of  the  coincident  use  of  all  the  rooms  usually  render  such  an 
arrangment  of  doubtful  utility. 


153 


VENTILATION  and  HEATING 


NEW  HAMPSHIRE  STATE  LIBRARY  AND  COURT  HOUSE,  CON- 
CORD, N.  H.  In  the  ordinary  court  room  are  presented  conditions  that  call  for 
an  ample  volume  of  air  and  its  thorough  distribution.  The  frequent  crowding  of  a 


criminal  court  room  with  the 
certain  to  be  accompanied 
Vile  odors  and  disease 
be  overcome  by  the 
A building 
of  a court  house 
91  and  92.  The 
broken  away  in 
the  height  of  two 
ters,  in  dues 


lowest  class  of  society  during  a sensational  trial,  is 
by  extraordinary  pollution  of  the  atmosphere, 
germs  are  rampant  and  their  effect  can  only 
most  bountiful  supply  of  pure,  fresh  air. 
devoted  to  the  combined  requirements 
and  a State  library  is  presented  in  Figs, 
court  room,  the  wall  of  which  is  shown 
Fig.  91 , extends  up  for 
stories.  Two  regis- 
located  in  the  inner 
wall,  force  the 


Fig.  91.  N.  H.  State  Library  and  Court  House,  Concord,  n.  H. 


air  toward  the  opposite  and  outer  wall,  whence,  following  the  downward  course, 
due  to  its  being  cooled,  it  returns  toward  the  inner  wall  and  escapes  through 
fireplaces  and  adjacent  registers  in  the  side  walls.  A separate  floor  register  is 
also  provided  for  supplying  the  judge’s  bench,  which  is  upon  the  outer  side  of 
the  room. 

The  adjoining  smaller  rooms,  devoted  to  uses  of  the  court  and  jury,  are 
treated  as  are  similar  apartments  in  other  buildings,  with  supply  from  overhead 
registers  in  the  inner  walls  and  ventilating  registers  at  floor  level  and  in  the 
same  walls  when  possible. 

The  library  portion  of  this  building,  as  will  be  seen  by  Fig.  92,  consists  of 
a main  stack  room  with  alcoves.  In  each  of  the  partition  walls  between  alcoves 


154 


VENTILATION  and  HEATING  « 


are  located  vertical  flues  from  which  hot  air  is  delivered  to  each  alcove,  thereby 
keeping'  their  most  exposed  portions  warm.  Thence  it  passes  to  the  main  room 
with  its  less  exposure,  whence  it  escapes  through  ventilating  registers,  as  indicated. 
The  great  value  of  the  books  of  a library  necessarily  demands  the  utmost  care  in 
the  introduction  of  the  heating  system  to  the  end  that  they  may  not  be  injured 


Fig.  92.  N.  H.  State  Lib.  and  C.  H.,  Concord,  n.  H.,  First  Floor  Plan. 


by  overheating.  In  this  case  the  air  is  admitted  above  the  tops  of  the  book 
stacks  in  such  a manner  as  to  prevent  its  immediate  contact  with  any  of  the 
volumes. 

The  apparatus,  located  in  the  basement,  near  the  centre  of  the  building,  is 
so  arranged  that  cold  air  may  be  conducted  to  the  bases  of  the  flues  to  the 
court  room,  where,  in  combination  with  the  hot  air  from  separate  ducts,  it  may 
be  admitted  to  the  court  room,  but  constantly  under  the  regulating  power  of 
thermostats,  which  thereby  maintain  a constant  temperature  within  the  apart- 
ment without  affecting  the  volume  of  air  admitted. 


155 


1 56 


Fig.  93.  First  Baptist  Church,  Malden,  Mass 


CHURCHES. 

The  treatment  of  a church  depends  largely  upon  its  design.  If  the  floor  is 
arranged  upon  the  amphitheatre  plan,  the  air  may  be  admitted  much  as  in  the 
case  of  a theatre.  But  the  usual  construction  presents  a floor  that  is  practically 
level  and  compels  the  introduction  of  air  vertically  through  it,  or  else  its  supply 
from  the  side  walls.  To  secure  the  best  distribution  the  latter  arrangement  is 
usually  adopted,  rendering  the  manner  of  heating  the  ordinary  church  but  little 
different  from  that  of  a hall  of  audience. 

The  intermittent  use  of  a church,  however,  introduces  one  of  the  most 
important  problems  in  the  design  and  introduction  of  a heating  and  ventilating 
system.  As  a rule,  upon  Sunday,  practically  all  the  rooms  in  the  building  are 
in  use,  sometimes  the  auditorium  and  Sunday-school  rooms  coincidently,  some- 
times consecutively,  while  less  frequently  one  is  occupied  in  the  morning  and 
the  other  in  the  afternoon.  Furthermore,  the  parlors,  pastor’s  study,  or  small 
lecture  rooms,  may  be  required  to  be  warmed  only  on  certain  days  of  the  week. 

Evidently,  then,  the  system  installed  must  be  varied  in  its  adaptability  and 
rapid  in  its  ability  to  warm  up  the  building  after  it  has  been  thoroughly  cooled 
down.  For  the  occasional  warming  of  small  rooms  where  ventilation  is  not  an 
all-essential  feature,  direct  radiation  will  be  found  most  advantageous,  while 
provision  may  also  be  made  for  supplying  air  to  the  same  apartments  when  the 
apparatus  is  in  operation. 

FIRST  BAPTIST  CHURCH,  MALDEN,  MASS.  In  the  structure  illus- 
trated in  part  in  Fig.  93,  the  auditorium  and  Sunday-school  are  located  upon 
the  same  floor,  the  latter  being  flanked  upon  two  sides  by  two  tiers  of  class- 
rooms and  parlors,  arranged  to  be  separated  from,  or  form  a part  of,  the  main 
room  at  will.  The  apparatus  is  located  in  the  basement,  near  the  centre  of  the 
structure,  and  pipes  extend  therefrom  to  the  various  vertical  flues,  the  location 
of  a sufficient  number  of  which  is  indicated  to  make  the  arrangement  clear. 
Each  flue  in  the  side  walls  of  the  auditorium  is  provided  with  two  registers, 
the  lower  at  floor  level,  to  be  employed  when  first  warming  up.  Ventilation 
takes  place  through  wall  registers  set  near  the  floor,  whence  the  foul  air  passes 
to  the  roof  space  and  out  of  a roof  ventilator. 

The  main  Sunday-school  room  is  supplied  and  ventilated  as  indicated  by 
the  location  of  the  registers,  while  the  classrooms  and  parlors  are  individually 
heated  and  ventilated.  Direct  steam  radiators  additionally  heat  certain  of  the 
apartments.  The  social  hall  in  the  basement  is  supplied  directly  from  the  fan. 


gsggjfcc:*, 


n 

1 

158 


Fig.  94.  Castle  Square  Theatre,  Boston,  Mass. 


VENTILATION  and  HEATING 


THEATRES. 

Theatres,  of  all  halls  of  audience,  require  the  greatest  care  and  the  most 
extended  experience  in  the  designing  of  a system  of  ventilation  and  heating 
adequate  for  their  requirements.  They  consist  of  three  different  parts:  the 
entire  body  of  the  house  or  auditorium ; the  stage  and  dressing  rooms ; and  the 
foyer,  lobbies,  corridors,  stairways  and  offices.  But  the  distinction  and  separa- 
tion between  these  different  parts  changes  at  different  times  during  a perform- 
ance. The  simple  rising  of  the  curtain  throws  into  one  the  two  previously 
distinct  apartments  — the  auditorium  and  the  stage.  So  too,  when  all  the  doors 
or  portieres  are  opened  into  the  corridors,  the  distinction  between  the  auditorium 
and  corridors  is  materially  lessened.  It  will  be  readily  seen  that  arrangements 
based  entirely  upon  the  constant  separation  of  these  various  apartments  may 
be  seriously  affected,  if  it  is  possible  to  so  suddenly  and  radically  change  these 
conditions. 

As  a rule,  theatres  are  located  in  cities  with  buildings  abutting  on  two  or 
more  sides  and  allowing  of  no  direct  connection,  by  windows,  with  the  external 
air.  In  fact,  none  but  artificial  means  can  ever  produce  satisfactory  results 
in  such  places,  and,  furthermore,  only  a system  of  forced  circulation  has  com- 
plete control  over  all  conditions.  Generally  speaking,  it  is  advisable  to  create  a 
slight  excess  of  pressure  in  the  auditorium,  in  order  that  all  openings  shall  allow 
for  the  discharge,  rather  than  for  the  ingress  of  air.  This  condition  will  cause 
the  curtain  to  swell  slightly  toward  the  stage,  and  will  ensure  the  leakage  of  air 
from  the  auditorium  to  the  corridors  rather  than  the  reverse,  which  under  certain 
conditions  may  be  decidedly  objectionable.  The  general  methods  of  air  intro- 
duction and  distribution  in  such  a building  have  already  been  pointed  out. 

The  close  seating  of  the  occupants  produces  a large  amount  of  animal  heat, 
generally  increasing  the  temperature  five  or  six  degrees  and,  quite  frequently, 
fully  ten  degrees,  evidently  so  much  that,  considering  a theatre  once  filled  and 
thoroughly  warmed,  it  usually  becomes  not  so  much  a question  of  warming 
as  of  cooling  to  produce  comfort.  Occupied  as  such  buildings  are  for  a number 
of  hours,  a continuous  working  system  must  be  provided,  and  no  reliance 
placed  on  one  that  puts  the  atmosphere  in  good  condition  at  the  beginning  of  a 
performance,  but  fails  to  maintain  that  good  condition  to  the  end.  Architects 
have  during  late  years  devoted  a great  deal  of  attention  to  this  matter,  with 
marked  improvement  in  the  condition  of  newly-constructed  theatres.  Many 
failures  have,  however,  resulted  from  inexperience,  and  a lack  of  realization  of 
extraordinary  requirements  in  such  structures. 


159 


VENTILATION  and  HEATING 


CASTLE  SQUARE  THEATRE,  BOSTON,  MASS.  Evidently  there  is 
great  opportunity  for  variety  in  the  heating  and  ventilating  arrangements  that 
may  be  introduced  in  a theatre.  While  side  wall  flues  and  openings  may  to  a 


Fig.  95.  Castle  Square  Theatre,  Boston, 
Mass.,  Basement  Plan. 


certain  extent  fulfil  the  requirements,  they  are,  nevertheless,  so  located  that  the 
air  discharged  therefrom  can  never  do  its  most  effective  work  in  the  way  of 
ventilation.  Although  the  system  of  ceiling  supply  by  means  of  a plenum  fan 


160 


VENTILATION  and  HEATING 


discharging  through  a perforated  ceiling,  with  a resulting  downward  movement 
of  the  air  enforced  by  an  exhaust  fan  drawing  from  floor  openings,  possesses 
many  advantages,  and  has  to  a considerable  extent  been  introduced,  yet  it  has 
seemed  advisable  to  illustrate  here  the  more  common  method  of  floor  supply 
and  upward  air  movement. 

In  this  theatre,  clearly  presented  in  its  general  arrangements  in  Figs.  94  and 
95,  there  is  practically  no  external  exposure, — only  a little  more  than  the  width 
of  the  doors  upon  either  side.  The  front  is  faced  with  a hotel,  as  is  also  the 
rear  of  the  stage.  Therefore,  the  entire  theatre  is,  to  all  practical  purposes, 
entirely  enclosed. 

The  skeleton  structure  is  of  steel  beam  and  girder  work,  while  all  arches, 
partitions  and  similar  portions  are  of  tile  or  terra-cotta,  making  an  ideally  fire- 
proof structure.  Immediately  surrounding  the  orchestra  circle  is  the  usual 
partition  separating  it  from  the  foyer  and  lobbies.  Above  the  level  of  the 
first  floor  this  partition  is  formed  of  a double  wall  of  terra-cotta,  with  space 
between.  The  space  in  the  basement  between  this  partition  and  the  outer  wall 
of  the  theatre  forms  a passage  or  conduit  some  ten  feet  in  height. 

Located  in  this  passage,  at  a point  convenient  to  the  fresh  air  supply  from 
above  the  roof,  is  a special  cone  fan  of  the  general  type  illustrated  in  Fig.  18,  set  to 
the  extent  of  about  half  its  diameter  into  a properly-shaped  pit.  Adjacent  thereto 
is  the  heater  enclosed  in  a brick  chamber,  while  an  engine  furnishes  the  motive 
power  to  drive  the  fan  by  belt.  The  air  (heated  or  otherwise,  as  may  be  nec- 
essary), as  it  leaves  the  fan,  passes  in  properly-proportioned  volumes  in  either 
direction  along  the  passage,  whence  the  greater  part  is  allowed  to  escape  to  the 
space  beneath  the  auditorium  proper.  In  smaller  volumes  it  is  delivered  to 
the  first  and  second  balconies  through  flues  in  the  pilasters  and  through  the 
hollow  walls  at  the  rear  of  the  auditorium.  Through  the  large  flues,  near  the 
boxes,  and  upon  either  side  of  the  auditorium,  air  passes  to  large  wall  registers, 
as  shown  in  the  section,  and  also  to  the  space  beneath  the  second  balcony  floor. 
The  boxes  are  supplied  through  special  flues,  which  discharge  into  the  passages 
with  which  they  connect,  whence  the  air  enters  the  boxes  beneath  the  doors, 
which  are  cut  short,  and  passes  across  the  occupants  to  the  body  of  the  house. 

The  principal  supply  for  the  auditorium  — amounting  to  nearly  30,000 
cubic  feet  per  minute  for  the  orchestra  and  orchestra  circle  alone,  and  as  much 
more  for  the  balconies, — is  admitted  through  the  floors  of  these  respective  por- 
tions. In  the  case  of  the  main  floor,  the  space  beneath  it  permits  of  the  ready 
distribution  of  the  air  admitted  thereto  through  the  numerous  openings  in  the 
basement  partition  wall. 


161 


VENTILATION  and  HEATING 


I lie  chair  legs  throughout  the  entire  house  are  provided  with  special 
latticed  castings,  as  shown  in  Fig.  96,  forming  thereby  a large  number  of  air 
chambers  to  which  air  is  discharged  through  openings  in  the  floor  immediately 
beneath  them.  The  air  thus  passing  through  the  floor  openings  at  relatively 
high  velocity  is  permitted  to  escape  beneath  the  persons  of  the  occupants  with 
low  and  imperceptible  movement,  and  then  pass  upward  to  the  ceiling  vents. 

These  vents,  consisting  of  a central  ceiling  opening  of  moderate  size  and 
numerous  smaller  openings  in  the  ceiling  at  the  back  of  the  second  balcony, 
provide  for  a backward  sweeping  movement  of  the  air  across  both  first  and 

second  balconies,  thereby  securing  the  highest 
efficiency  from  a given  volume  of  air.  Special 
ventilation  from  the  orchestra  circle  and  the 
extreme  rear  of  the  first  balcony  is  also  indi- 
cated in  the  sectional  view.  From  the  roof 
space  to  which  all  this  foul  air  passes,  it  is 
exhausted  by  a large  electrically  driven  cone 
fan,  located  upon  the  roof  above  the  stage  and 
discharging  freely  into  the  atmosphere. 

All  escape  of  odors  from  the  toilet  and 
smoking  rooms  to  other  apartments  is  avoided 
by  providing  special  and  positive  exhaust  venti- 
lation therefrom  by  means  of  an  exhaust  fan, 
located  in  the  basement,  which  connects  with 
a series  of  vertical  flues.  The  same  fan  also  serves  to  remove  the  heated  air  and 
odors  from  the  kitchen  and  the  boiler  and  dynamo  rooms  beneath  the  hotel. 

The  foyer  is  supplied  with  warm  air  through  registers  in  the  walls  beneath 
the  stairs,  and  is  independently  ventilated  through  its  triple-domed  ceiling.  The 
stage  is  heated  by  means  of  steam  coils  at  the  back  suspended  just  beneath  the 
floor,  cast-ircn  gratings  being  provided  through  which  the  heated  air  may  pass 
upward. 

The  temperature  throughout  the  auditorium  is  regulated  by  a thermostat 
arranged  to  operate  a by-pass  damper  on  the  heater,  so  that  any  desired  tem- 
perature of  the  air  passing  to  the  conduit  may  be  secured.  To  avoid  trouble 
from  too  great  and  sudden  cooling  of  the  air,  a minimum  thermostat  is  also 
introduced,  which,  as  usually  set,  prevents  the  admission  of  air  to  the  auditorium 
at  a temperature  lower  than  65°.  With  this  arrangement  this  temperature  is 
readily  and  uniformly  maintained  at  70°  throughout  the  house,  while  30  cubic 
feet  and  over  is  supplied  per  minute  to  each  occupant. 


162 


VENTILATION  and  HEATING« 


DWELLINGS  AND  OTHER  BUILDINGS. 

While  characteristic  types  have  been  chosen  for  illustration  in  the  pre- 
ceding pages,  it  must  be  evident  that  it  is  impossible  in  this  comparatively 
small  compass  to  completely  cover  the  wide  range  of  variety  in  the  construction 
and  uses  of  buildings.  The  dwelling  house,  for  instance,  has  not  been  pre- 
sented, but  it  by  no  means  follows  that  its  ventilation  and  heating  may  not  be 
easily  accomplished.  Simply  because  of  the  similarity  of  treatment  of  an  office 
building  and  a dwelling  the  latter  has  not  been  illustrated. 

While  the  Sturtevant  System  meets  the  requirements  of  domestic  heating 
and  ventilation,  nevertheless,  because  of  its  mechanical  nature  it  is  more  or  less 
unsuitable  for  introduction  in  a moderate-sized  dwelling.  But  in  the  large 
private  residence  or  in  the  apartment  house,  where  careful  attendance  is  assured, 
it  evidently  surpasses  any  other  method.  Objectionable  furnace  gas  is  avoided, 
danger  from  leaking  direct-steam  or  hot-water  radiators  cannot  occur,  and  the 
supply  of  air  is  no  longer  at  the  mercy  of  the  atmospheric  changes. 

In  its  most  perfect  form  the  hot  and  cold  arrangement  of  the  system 
should,  of  course,  be  installed ; but  the  single-pipe  system  will,  under  ordinary 
conditions,  meet  the  requirements  of  good  ventilation,  for  the  air  supply  by 
the  Sturtevant  System  is  usually  far  in  excess  of  the  requirements.  The  perfec- 
tion of  the  electric  motor  and  the  extension  of  power  circuits  is  simplifying  the 
introduction  of  the  system  in  dwellings,  for  under  such  conditions  of  power 
supply  low-pressure  steam  may  be  employed  for  the  heating  and  the  speed  of 
the  motor,  and  consequently  the  movement  of  the  fan  readily  regulated. 

For  either  the  permanent  or  temporary  heating  of  large,  open  structures 
like  exhibition  buildings  this  system  is  particularly  adapted.  It  secures  uni- 
formity in  the  warming,  and  by  means  of  an  apparatus  that  is  readily  portable. 
The  Horticultural  Building,  at  the  World’s  Columbian  Exhibition,  was  thus 
treated,  apparatus  of  large  capacity  being  placed  within  the  huge  floral  mound 
which  stood  just  beneath  the  dome.  From  the  highest  point  of  this  mound  the 
warm  air  was  discharged,  volcano-like,  toward  the  glass-roofed  dome,  whence  by 
its  cooling  action  it  gradually  setttled  to  the  floor  and  was  thence  drawn  back 
once  more  to  the  apparatus.  Evidently,  after  the  Fair,  the  various  apparatus, 
unlike  a lot  of  direct-steam  piping,  were  still  in  marketable  form. 

The  Sturtevant  System  has  been  extensively  employed  for  the  double  pur- 
poses of  heating  dye  houses,  paper  mills,  and  the  like,  where  great  quantities  of 
steam  are  produced,  and  of  clearing  the  interior  atmosphere  by  absorbing  this 
steam  by  means  of  the  large  volumes  of  heated  air. 


VENTILATION  and  HEATING  « 


Fig.  97.  Steamships  “St.  Paul”  and  “St.  Louis.” 


164 


VENTILATION  and  HEATING  M 


STEAMSHIPS. 

While  efforts  are  continually  being  made  by  all  the  great  steamship  com- 
panies, notably  those  that  compete  for  the  travel  between  Europe  and  America, 
to  improve  their  ships,  reduce  their  time  of  passage,  and  to  make  comfortable 
the  passengers,  no  expense  being  spared  in  decorations  and  luxurious  fittings  of 
the  saloons  and  rooms  which  are  the  temporary  home  of  travellers,  it  is  a 
pleasure  to  be  able  to  record  the  fact  that  the  matter  of  ventilation  is  now 
receiving  its  share  of  attention.  There  is  no  doubt  that  one  of  the  greatest 
defects  in  a modern  steamship  has  been  the  failure  to  provide  an  adequate  and 
constant  supply  of  pure  air  at  all  times  and  in  all  parts  of  the  ship  that  are 
occupied  by  passengers  and  crew.  Much  of  the  discomfort  of  an  ocean  voyage, 
including  seasickness,  arises  from  the  bad  air  which  every  one  is  obliged  to 
breathe  when  below  decks  with  the  air  ports  closed,  especially  in  rough  weather. 
The  remedy  is  simple,  effectual  and  inexpensive.  By  means  of  a fan  the  state- 
rooms and  saloons  can  be  given  the  freshness  of  the  outer  air,  instead  of  the 
stuffy  and  oppressive  atmosphere  that  now  characterizes  them. 

The  problem  is  of  equal  importance  in  naval  vessels,  and  the  course  of  its 
inception  and  successful  solution  in  the  American  Navy  has  had  a great  influence 
in  leading  the  merchant  marine  to  adopt  this  most  beneficent  improvement. 

In  March,  1878,  the  Secretary  of  the  Navy  appointed  a board  of  officers 
“ to  examine  and  ascertain  the  best  system  of  ventilation,  by  mechanical  means 
or  otherwise,  by  which  the  ships  of  the  Navy  may  be  more  perfectly  ventilated 
than  at  the  present  time.”  This  board  made  an  examination  of  the  U.  S.  S. 
“ Richmond,”  and  reported : First,  upon  the  necessity  of  ventilation,  showing 
“ the  filthy  condition  of  the  atmosphere  generally  on  shipboard,  which  both 
men  and  officers  are  compelled  to  breathe ; thus  inducing  disease,  impairing 
health  and  increasing  the  mortality.”  Second,  upon  the  necessity  of  some 
mechanical  device  to  keep  up  the  circulation  of  air,  giving  reasons  why  “ no 
system  of  ventilation  can  be  relied  upon  which  depends  for  action  on  induced 
currents  produced  by  the  difference  of  densities  or  the  difference  in  the  static 
and  dynamic  heads  of  the  internal  and  external  air.”  As  a mechanical  device 
for  ventilating,  it  was  recommended  “ that  a fan  of  the  most  improved  type, 
and  one  that  has  been  thoroughly  tested  and  found  efficient,  be  adopted.” 

Two  fans,  the  first  constructed  for  this  purpose,  were  built  by  B.  F.  Sturte- 
vant.  After  twenty -five  days  at  sea,  Chief  Engineer  Baker  wrote : “ It  may  be 
confidently  stated,  that  the  ‘ Richmond  ’ is  now  by  far  the  most  completely  venti- 
lated ship  that  ever  sailed  under  the  American  flag,  or,  indeed,  under  any  flag.” 


165 


VENTILATION  and  HEATING 


STEAMSHIPS  “ST.  PAUL”  AND  “ST.  LOUIS.”  These  magnificent 
new  twin  transatlantic  liners  of  the  International  Navigation  Co.  undoubtedly 
stand  to-day  as  the  most  perfectly  heated  and  ventilated  vessels  afloat.  All 
other  mean's  of  heating  were  discarded,  and  the  Sturtevant  System  adopted 
throughout.  The  system  is  duplex  in  its  operation,  one  series  of  fans,  with 
their  attached  heaters,  serving  to  furnish  pure  warm  air  to  practically  all  occupied 
portions  of  the  ships,  while  a separate  set  of  exhausting  fans  is  arranged  to 
withdraw  the  air,  and  to  thereby  compel  its  complete  circulation. 

The  presence  of  water-tight  bulkheads  naturally  prevented  the  horizontal 
extension  of  air  pipes  throughout  the  lower  decks.  Four  separate  plants  were 
therefore  introduced,  each  plant  consisting  of  a heating  and  an  exhausting 
apparatus,  both  located 
on  the  shade  deck,  and 
driven  by  direct-con- 
nected electric  motors. 

From  each  of  these 
apparatus  pipes  extend 
downward,  and  upon 
each  deck  connect  with 
horizontal  systems  ; no 
pipes  passing  through 
the  transverse  bulk- 
heads. The  general 
scheme  of  this  arrange- 
ment is  indicated  in 
Fig.  97,  showing,  in 
outline,  a longitudinal 
section  and  plan  of  the  shade  deck  which  embraces  one  of  these  systems. 
Smaller  auxiliary  fans,  one  shown  on  either  side  of  the  ship,  supply  fresh,  cool 
air  direct  to  the  engine  rooms,  while  the  large  fan,  presented  in  side  elevation, 
is  devoted  solely  to  exhausting  from  the  galley. 

All  pipes  are  carried  close  up  to  the  deck  or  deck  beams  above.  On  the 
berth  deck  the  supply  ducts  are  extended  down  each  of  the  stateroom  alcoves, 


T 


Fig.  98. 
Stateroom 


discharging  the  air  overhead  toward  the  side  of  the  ship,  as  indicated  in  Fig.  98. 


Positive  circulation  throughout  the  stateroom  is  accomplished  by  extending  an 
exhaust  pipe  down  behind  the  commode  and  dressing  case,  as  shown,  and  pro- 
viding it  at  the  bottom  with  a suitable  opening.  The  latticed  panel  permits  of 
ready  passage  of  air  when  the  door  is  closed. 


166 


VENTILATION  and  HEATING 


0 


TESTING  SYSTEMS  OF  VENTILATION  AND 

HEATING. 


The  actual  efficiency  of  any  system  of  ventilation  and  heating  cannot  be 
ascertained  by  mere  casual  inspection,  but  only  by  careful,  intelligent  and  exten- 
sive experiment.  Trustworthy  results  can  only  be  obtained  by  the  use  of 
special  instruments  designed  for  such  investigations. 

Among  the  most  important  for  this  purpose  are 
those  here  presented. 

Good  thermometers,  of  the  usual  construction, 
are  generally  sufficiently  accurate  for  observing  the 
ordinary  temperature  of  air,  but  for  noting 
the  temperature  of  steam,  or  of  highly- 
heated  air,  the  form  shown  in  Fig.  99  is 
very  convenient.  The  thermometer  tube 
is  enclosed  in  a tubular  brass  case,  the 
lower  end  of  which  is  provided  with  a 
screw  of  standard  size  and  thread,  by 

means  of  which  it  may  be  securely  in-  p,G>  100>  ANEMOMETER, 
serted  in  any  T or  flange.  The  tube  pro- 
jects well  down  below  the  threaded  portion,  and  is  guarded  by  a small 
pipe  attached  to  the  bottom  of  the  case,  which  allows  free  circulation 
around  the  bulb  of  the  thermometer.  The  glass  may  be  graduated  to 
read  between  any  given  temperatures.  For  instance,  if  the  ther- 
mometer is  to  be  employed  exclusively  for  ascertaining  the  ordinary 
temperature  of  steam,  its  range  need  not  be  greater  than  between  the 
points  200°  to  350°. 

Under  ordinary  conditions  the  volume  of  air  flowing  through  a 
given  passage  or  orifice  may  be  most  readily  determined  by  means  of 


an  anemometer.  This  instrument,  of  the  form  illustrated  in  Fig.  100, 


consists  of  a light  and  delicately  constructed  fan  wheel  whose 
motion  is  transmitted  to  a practically  frictionless  system  of 
gearing  within  the  attached  case.  The  movement  of  this 
system  of  gearing  is  rendered  evident  by  the  hands  and 
graduated  circles  upon  the  dial.  The  velocity  of  the  air,  in 
feet  per  minute,  is  indicated  thereon,  the  series  indicating 
100,  1,000,  10,000,  100,000,  1,000,000  and  10,000,000 


Fig.  99.  High-Grade 
Thermometer. 


167 


VENTILATION  and  HEATING 


respectively. 


Evidently  the  velocity  thus  obtained,  corrected  for  any  known 
error  of  the  instrument,  multiplied  by 
the  area  of  the  passage,  must  give  the 
total  volume  of  air  passing. 

Air  pressures  may  be  determined  by 
means  of  the  ordinary  U tube,  one  end 
being  connected  with  the  given  space  or 
passage  and  the  other  with  the  atmos- 
phere, the  difference  in  pressure  being 
indicated  by  the  difference  in  level  of 
the  water  in  the  two  legs  of  the  tube. 
This  reading  of  pressure  differences  in 
inches  of  water  may  be  readily  trans- 
formed into  pressure  in  ounces  by  multi- 
plying by  .578  — this  factor  being  the 
equivalent,  in  ounces,  of  the  pressure 
due  to  a head  of  one  inch  of  water. 

The  humidity  of  the  air  may  be 
ascertained  by  a hygrometer,  shown  in 
its  most  convenient  form  in  Fig.  101. 
It  is  provided  with  two  standard  ther- 
mometers, one — the  dry  bulb  — show- 
ing the  temperature  of  the  air,  the  other 
— the  wet  bulb  — the  temperature  due 
to  evaporation.  When  the  air  is  satur- 
ated no  evaporation  takes  place,  and  the 
two  thermometers  indicate  the  same. 
Between  the  thermometers,  and  enclosed 
in  the  case  behind  the  slot,  is  a cylinder 
arranged  to  be  freely  turned  by  the  knob 
at  the  top,  and  upon  which  is  inscribed 
a series  of  columns  of  figures  numbered 
i yj*  their  headings. 

'VTbe  instrument  here  shown  was  spe- 
cialty \lesigned  for  high  temperatures, 
;|and  a /double  set  of  columns  is  given. 
These  numbers  represent  the  difference 
Fig.  101.  Hygrometer.  , in -temperature  shown  by  the  two  ther- 


168 


VENTILATION  and  HEATING 


mometers.  The  vertical  columns  beneath  them  exhibit  the  relative  humidity, 
which  may  be  read  off  beneath  the  figures  at  top  of  column,  indicating  the 
difference  of  temperatures,  and  opposite  to  the  temperature  of  the  wet  bulb,  as 
shown  on  the  scale  at  the  left  of  the  cylinder. 

The  amount  of  carbonic  acid  present  in  the  atmosphere  may  be  readily 
ascertained  to  a sufficiently  close  degree  for  practical  purposes  in  the  following 
manner.  Six  clean,  dry  and  well -stoppered  bottles,  containing  respectively  100, 
200,  2 50,  300,  350  and  400  cubic  centimeters,  a glass  tube  containing  exactly 

15  cubic  centimeters  to  a given  mark,  and  a bottle  of  perfectly  clear,  fresh  lime- 
water,  constitute  the  apparatus  required.  The  bottles  should  be  filled  by  means 
of  a hand-ball  syringe  with  the  atmosphere  to  be  examined.  Add  to  the 
smallest  bottle  15  cubic  centimeters  of  the  lime-water,  put  in  the  cork  and 
shake  well.  If  turbidity  appears,  the  amount  of  carbonic  acid  will  be  at  least 

16  parts  in  10,000.  If  no  turbidity  appears,  treat  the  bottle  of  200  cubic  centi- 
meters in  the  same  manner;  turbidity  in  this  would  indicate  12  parts  in  10,000. 
In  similar  manner,  turbidity  in  the  2 50  cubic  centimeter  bottle  indicates  at  least 
10  parts  in  10,000;  in  the  300,  8 parts;  in  the  3 50,  7 parts;  and  in  the  400, 
less  than  6 parts.  The  ability  to  conduct  more  accurate  analyses  can  only  be 
attained  by  special  study  and  a knowledge  of  chemical  properties  and  methods 
of  investigation. 


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